U.S. patent application number 16/248435 was filed with the patent office on 2019-12-26 for adjustable gain devices and methods for use tehrewith.
This patent application is currently assigned to Futurewei Technologies, Inc.. The applicant listed for this patent is Futurewei Technologies, Inc.. Invention is credited to Paul R. Ganci, Matthew R. Miller.
Application Number | 20190393915 16/248435 |
Document ID | / |
Family ID | 65322900 |
Filed Date | 2019-12-26 |
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United States Patent
Application |
20190393915 |
Kind Code |
A1 |
Miller; Matthew R. ; et
al. |
December 26, 2019 |
ADJUSTABLE GAIN DEVICES AND METHODS FOR USE TEHREWITH
Abstract
The disclosure relates to technology for an adjustable gain
device that includes differential input terminals, differential
output terminals, signal processing circuitry, and first and second
cross-coupled segments. The first cross-coupled segment is coupled
between differential input terminals of the adjustable gain device
and a negative input of the signal processing circuitry. The second
cross-coupled segment is coupled between differential input
terminals of the adjustable gain device and a positive input of the
signal processing circuitry. The adjustable gain device has a gain
that is adjustable by adjusting values of the first and second
cross-coupled segments, while maintaining a substantially
consistent frequency response and a substantially consistent input
impedance of the adjustable gain device, so long as a specified
relationship between values of the first and second cross-coupled
segments is kept substantially constant.
Inventors: |
Miller; Matthew R.;
(Arlington Heights, IL) ; Ganci; Paul R.; (Golden,
CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Futurewei Technologies, Inc. |
Plano |
TX |
US |
|
|
Assignee: |
Futurewei Technologies,
Inc.
Plano
TX
|
Family ID: |
65322900 |
Appl. No.: |
16/248435 |
Filed: |
January 15, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16015926 |
Jun 22, 2018 |
10211865 |
|
|
16248435 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H03F 2200/144 20130101;
H03F 3/45475 20130101; H03F 2200/387 20130101; H03F 2203/45528
20130101; H03H 11/126 20130101; H03F 2203/45591 20130101; H03F
2203/45526 20130101; H03H 11/1291 20130101; H03F 2200/451 20130101;
H03F 2203/45576 20130101; H03F 2200/331 20130101; H03H 11/28
20130101; H03F 2203/45138 20130101; H03D 2200/0025 20130101; H03F
2200/267 20130101; H03F 2203/45512 20130101; H03G 1/0088 20130101;
H03F 2200/294 20130101; H03D 7/12 20130101; H03F 2200/129 20130101;
H03F 2200/222 20130101; H03F 3/19 20130101; H03F 2200/171 20130101;
H03F 2203/45116 20130101; H03F 3/45071 20130101; H03F 3/195
20130101; H03G 3/3052 20130101; H03H 2210/017 20130101; H04B 1/16
20130101; H03F 2203/45134 20130101 |
International
Class: |
H04B 1/16 20060101
H04B001/16; H03H 11/12 20060101 H03H011/12; H03F 3/45 20060101
H03F003/45; H03F 3/19 20060101 H03F003/19; H03D 7/12 20060101
H03D007/12; H03H 11/28 20060101 H03H011/28; H03G 3/30 20060101
H03G003/30 |
Claims
1. An adjustable gain device, comprising: differential input
terminals and differential output terminals of the adjustable gain
device; signal processing circuitry between the differential input
terminals and the differential output terminals of the adjustable
gain device; a first cross-coupled segment coupled between the
differential input terminals of the adjustable gain device and a
negative (-) input of the signal processing circuitry; and a second
cross-coupled segment coupled between the differential input
terminals of the adjustable gain device and a positive (+) input of
the signal processing circuitry; the adjustable gain device
configured to have a gain that is adjustable by adjusting one or
more component values of the first and second cross-coupled
segments; and the adjustable gain device configured to maintain a
substantially consistent frequency response and a substantially
consistent input impedance when the gain of the adjustable gain
device is adjusted by adjusting the one or more component values of
the first and second cross-coupled segments.
2. The adjustable gain device of claim 1, wherein the adjustable
gain device is selected from the group consisting of: a
multi-feedback (MFB) filter; a variable gain amplifier (VGA); a
sigma-delta analog-to-digital converter (ADC); a mixer configured
to perform frequency down-conversion; or a mixer configured to
perform frequency up-conversion.
3. The adjustable gain device of claim 1, wherein the substantially
consistent frequency response and the substantially consistent
input impedance of the adjustable gain device are maintained, when
the gain of the adjustable gain device is adjusted by adjusting the
one or more component values of the first and second cross-coupled
segments, by keeping substantially constant a specified
relationship between the component values of the first and second
cross-coupled segments.
4. The adjustable gain device of claim 3, further comprising a
controller configured to adjust the component values of the first
and second cross-coupled segments to achieve different gain
settings of the adjustable gain device, while maintaining the
substantially consistent frequency response and the substantially
consistent input impedance of the adjustable gain device, by
keeping substantially constant the specified relationship between
the component values of the first and second cross-coupled
segments.
5. The adjustable gain device of claim 3, wherein: the first
cross-coupled segment includes a first passive component having a
first adjustable component value and a second passive component
having a second adjustable component value; and the second
cross-coupled segment includes a third passive component having the
first adjustable component value and a fourth passive component
having the second adjustable component value.
6. The adjustable gain device of claim 5, wherein: the first
passive component of the first cross-coupled segment is a first
impedance component having a first adjustable impedance value
(Z1a); the second passive component of the first cross-coupled
segment is a second impedance component having a second adjustable
impedance value (Z1b); the third passive component of the second
cross-coupled segment is a third impedance component having the
first adjustable impedance value (Z1a); the fourth passive
component of the second cross-coupled segment is a fourth impedance
component having the second adjustable impedance value (Z1b); the
gain of the adjustable gain device is adjustable by adjusting the
first adjustable impedance value (Z1a) and the second adjustable
impedance value (Z1b), and the specified relationship between the
component values of the first and second cross-coupled segments
that is kept substantially constant to maintain the substantially
consistent frequency response and the substantially consistent
input impedance of the adjustable gain device, when the gain of the
adjustable gain device is adjusted, comprises: Z 1 a ( s ) * Z 1 b
( s ) Z 1 a ( s ) + Z 1 b ( s ) ##EQU00016## for each value of s,
wherein s is a variable that represents complex frequency.
7. The adjustable gain device of claim 6, wherein: the first
impedance component is a first resistor component having a first
adjustable resistance value (R1a), and thus, the first adjustable
impedance value (Z1a) of the first impedance component is equal to
R1a, the second impedance component is a second resistor component
having a second adjustable resistance value (R1b), and thus, the
second adjustable impedance value (Z1b) of the second impedance
component is equal to R1b; the third impedance component is a third
resistor component having the first adjustable resistance value
(R1a), and thus, the first adjustable impedance value (Z1a) of the
third impedance component is equal to R1a; the fourth impedance
component is a fourth resistor component having the second
adjustable resistance value (R1b), and thus, the second adjustable
impedance value (Z1b) of the fourth impedance component is equal to
R1b; the gain of the adjustable gain device is adjustable by
adjusting the first adjustable resistance value (R1a) and the
second adjustable resistance value (R1b), and the specified
relationship between the component values of the first and second
cross-coupled segments that is kept substantially constant to
maintain the substantially consistent frequency response and the
substantially consistent input impedance of the adjustable gain
device, when the gain of the adjustable gain device is adjusted,
comprises: R 1 a * R 1 b R 1 a + R 1 b . ##EQU00017##
8. The adjustable gain device of claim 6, wherein: the first
impedance component is a first capacitor component having a first
adjustable capacitance value (C1a), and thus, the first adjustable
impedance value (Z1a) of the first impedance component is equal to
1/(s*C1a), the second impedance component is a second capacitor
component having a second adjustable capacitance value (C1b), and
thus, the second adjustable impedance value (Z1b) of the second
impedance component is equal to 1/(s*C1b), the third impedance
component is a third capacitor component having the first
adjustable capacitance value (C1a), and thus, the first adjustable
impedance value (Z1a) of the third impedance component is equal to
1/(s*C1a); the fourth impedance component is a fourth capacitor
component having the second adjustable capacitance value (C1b), and
thus, the second adjustable impedance value (Z1b) of the fourth
impedance component is equal to 1/(s*C1b); the gain of the
adjustable gain device is adjustable by adjusting the first
adjustable capacitor value (C1a) and the second adjustable
capacitance value (C1b) of each of the second capacitor component
of the first cross-coupled segment and the fourth capacitor
component of the second cross-coupled segment; and the specified
relationship between the component values of the first and second
cross-coupled segments that is kept substantially constant to
maintain the substantially consistent frequency response and the
substantially consistent input impedance of the adjustable gain
device, when the gain of the adjustable gain device is adjusted,
comprises: C1a+C1b
9. The adjustable gain device of claim 6, wherein: the first
impedance component is a first inductor component having a first
adjustable inductance value (L1a), and thus, the first adjustable
impedance value (Z1a) of the first impedance component is equal to
(s*L1a); the second impedance component is a second inductor
component having a second adjustable inductance value (L1b), and
thus, the second adjustable impedance value (Z1b) of the second
impedance component is equal to (s*L1b), the third impedance
component is a third inductor component having the first adjustable
inductance value (L1a), and thus, the first adjustable impedance
value (Z1a) of the third impedance component is equal to (s*L1a),
the fourth impedance component is a fourth inductor component
having the second adjustable inductance value (L1b), and thus, the
second adjustable impedance value (Z1b) of the fourth impedance
component is equal to (s*L1b), the gain of the adjustable gain
device is adjustable by adjusting the first adjustable inductor
value (L1a) and the second adjustable inductance value (L1b) of
each of the second inductor component of the first cross-coupled
segment and the fourth inductor component of the second
cross-coupled segment; and the specified relationship between the
component values of the first and second cross-coupled segments
that is kept substantially constant to maintain the substantially
consistent frequency response and the substantially consistent
input impedance of the adjustable gain device, when the gain of the
adjustable gain device is adjusted, comprises: ( L 1 a * L 1 b ) L
1 a + L 1 b . ##EQU00018##
10. The adjustable gain device of claim 1, wherein signal
processing circuitry includes positive (+) and negative (-) outputs
that provide the differential output terminals of the adjustable
gain device.
11. A method for use with an adjustable gain device including
differential input terminals and differential output terminals, and
also including signal processing circuitry between the differential
input terminals and the differential output terminals of the
adjustable gain device, the method comprising: providing a first
cross-coupled segment between the differential input terminals of
the adjustable gain device and a negative (-) input of the signal
processing circuitry; and providing a second cross-coupled segment
between the differential input terminals of the adjustable gain
device and a positive (+) input of the signal processing circuitry;
and adjusting a gain of the adjustable gain device, while
maintaining a substantially consistent frequency response and a
substantially consistent input impedance of the adjustable gain
device, by adjusting one or more component values of the first and
second cross-coupled segments while keeping substantially constant
a specified relationship between the component values of the first
and second cross-coupled segments.
12. The method of claim 11, wherein: the first cross-coupled
segment includes a first passive component having a first
adjustable component value and a second passive component having a
second adjustable component value; the second cross-coupled segment
includes a third passive component having the first adjustable
component value and a fourth passive component having the second
adjustable component value; and the adjusting the gain of the
adjustable gain device, while maintaining the substantially
consistent frequency response and the substantially consistent
input impedance of the adjustable gain device, comprises adjusting
the first adjustable component value of each of the first passive
component of the first cross-coupled segment and the third passive
component of the second cross-coupled segment, and adjusting the
second adjustable component value of each of the second passive
component of the first cross-coupled segment and the fourth passive
component of the second cross-coupled segment, while keeping
substantially constant the specified relationship between the
component values of the first and second cross-coupled
segments.
13. The method of claim 12, wherein: the first passive component of
the first cross-coupled segment is a first impedance component
having a first adjustable impedance value (Z1a); the second passive
component of the first cross-coupled segment is a second impedance
component having a second adjustable impedance value (Z1b), the
third passive component of the second cross-coupled segment is a
third impedance component having the first adjustable impedance
value (Z1a); the fourth passive component of the second
cross-coupled segment is a fourth impedance component having the
second adjustable impedance value (Z1b), the adjusting the gain of
the adjustable gain device comprises adjusting the first adjustable
impedance value (Z1a) and the second adjustable impedance value
(Z1b), and the specified relationship between the component values
of the first and second cross-coupled segments that is kept
substantially constant to maintain the substantially consistent
frequency response and the substantially consistent input impedance
of the adjustable gain device, when the gain of the adjustable gain
device is adjusted, comprises: Z 1 a ( s ) * Z 1 b ( s ) Z 1 a ( s
) + Z 1 b ( s ) ##EQU00019## for each value of s, wherein s is a
variable that represents complex frequency.
14. The method of claim 13, wherein: the first impedance component
is a first resistor component having a first adjustable resistance
value (R1a), and thus, the first adjustable impedance value (Z1a)
of the first impedance component is equal to R1a; the second
impedance component is a second resistor component having a second
adjustable resistance value (R1b), and thus, the second adjustable
impedance value (Z1b) of the second impedance component is equal to
R1b; the third impedance component is a third resistor component
having the first adjustable resistance value (R1a), and thus, the
first adjustable impedance value (Z1a) of the third impedance
component is equal to R1a; the fourth impedance component is a
fourth resistor component having the second adjustable resistance
value (R1b), and thus, the second adjustable impedance value (Z1b)
of the fourth impedance component is equal to R1b; the adjusting
the gain of the adjustable gain device comprises adjusting the
first adjustable resistance value (R1a) and the second adjustable
resistance value (R1b), and the specified relationship between the
component values of the first and second cross-coupled segments
that is kept substantially constant to maintain the substantially
consistent frequency response and the substantially consistent
input impedance of the adjustable gain device, when the gain of the
adjustable gain device is adjusted, comprises: R 1 a * R 1 b R 1 a
+ R 1 b . ##EQU00020##
15. The method of claim 13, wherein: the first impedance component
is a first capacitor component having a first adjustable
capacitance value (C1a), and thus, the first adjustable impedance
value (Z1a) of the first impedance component is equal to 1/(s*C1a),
the second impedance component is a second capacitor component
having a second adjustable capacitance value (C1b), and thus, the
second adjustable impedance value (Z1b) of the second impedance
component is equal to 1/(s*C1b), the third impedance component is a
third capacitor component having the first adjustable capacitance
value (C1a), and thus, the first adjustable impedance value (Z1a)
of the third impedance component is equal to 1/(s*C1a), the fourth
impedance component is a fourth capacitor component having the
second adjustable capacitance value (C1b), and thus, the second
adjustable impedance value (Z1b) of the fourth impedance component
is equal to 1/(s*C1b); the adjusting the gain of the adjustable
gain device comprises adjusting the first adjustable capacitor
value (C1a) and the second adjustable capacitance value (C1b) of
each of the second capacitor component of the first cross-coupled
segment and the fourth capacitor component of the second
cross-coupled segment; and the specified relationship between the
component values of the first and second cross-coupled segments
that is kept substantially constant to maintain the substantially
consistent frequency response and the substantially consistent
input impedance of the adjustable gain device, when the gain of the
adjustable gain device is adjusted, comprises: C1a+C1b
16. A receiver, comprising: a low noise amplifier (LNA) configured
to amplify a radio frequency (RF) signal; a mixer downstream of the
LNA and configured to frequency convert the RF signal following
amplification thereof by the LNA; and an adjustable gain device
downstream of the mixer and configured to at least one of filter or
amplify the RF signal following the frequency conversion thereof by
the mixer, the adjustable gain device including: differential input
terminals and differential output terminals of the adjustable gain
device; signal processing circuitry between the differential input
terminals and the differential output terminals of the adjustable
gain device; a first cross-coupled segment coupled between the
differential input terminals of the adjustable gain device and a
negative (-) input of the signal processing circuitry; and a second
cross-coupled segment coupled between the differential input
terminals of the adjustable gain device and a positive (+) input of
the signal processing circuitry; the adjustable gain device
configured to have a gain that is adjustable by adjusting one or
more component values of the first and second cross-coupled
segments; and the adjustable gain device configured to maintain a
substantially consistent frequency response and a substantially
consistent input impedance when the gain of the adjustable gain
device is adjusted by adjusting the one or more component values of
the first and second cross-coupled segments.
17. The receiver of claim 16, wherein the substantially consistent
frequency response and the substantially consistent input impedance
of the adjustable gain device are maintained, when the gain of the
adjustable gain device is adjusted by adjusting the one or more
component values of the first and second cross-coupled segments, by
keeping substantially constant a specified relationship between the
component values of the first and second cross-coupled
segments.
18. The receiver of claim 17, further comprising a controller
configured to adjust the component values of the first and second
cross-coupled segments to achieve different gain settings of the
adjustable gain device, while maintaining the substantially
consistent frequency response and the substantially consistent
input impedance of the adjustable gain device, by keeping
substantially constant the specified relationship between the
component values of the first and second cross-coupled
segments.
19. The receiver of claim 17, wherein: the first cross-coupled
segment includes a first passive component having a first
adjustable component value and a second passive component having a
second adjustable component value; the second cross-coupled segment
includes a third passive component having the first adjustable
component value and a fourth passive component having the second
adjustable component value; the first passive component of the
first cross-coupled segment is a first impedance component having a
first adjustable impedance value (Z1a); the second passive
component of the first cross-coupled segment is a second impedance
component having a second adjustable impedance value (Z1b), the
third passive component of the second cross-coupled segment is a
third impedance component having the first adjustable impedance
value (Z1a); the fourth passive component of the second
cross-coupled segment is a fourth impedance component having the
second adjustable impedance value (Z1b), the gain of the adjustable
gain device is adjustable by adjusting the first adjustable
impedance value (Z1a) and the second adjustable impedance value
(Z1b), and the specified relationship between the component values
of the first and second cross-coupled segments that is kept
substantially constant to maintain the substantially consistent
frequency response and the substantially consistent input impedance
of the adjustable gain device, when the gain of the adjustable gain
device is adjusted, comprises: Z 1 a ( s ) * Z 1 b ( s ) Z 1 a ( s
) + Z 1 b ( s ) ##EQU00021## for each value of s, wherein s is a
variable that represents complex frequency.
20. The receiver of claim 16, wherein: the adjustable gain device,
which is coupled downstream of the mixer, is selected from the
group consisting of: a low pass filter (LPF); a bandpass filter
(BPF); a high pass filter (HPF); or a variable gain amplifier
(VGA); and the receiver is configured to be included in user
equipment or a base station used to communicate data within a
wireless network.
Description
PRIORITY CLAIM
[0001] This application is a continuation of U.S. patent
application Ser. No. 16/015,926, filed Jun. 22, 2018 which is
incorporated herein by reference.
CROSS-REFERENCE
[0002] This application is related to commonly invented and
commonly assigned U.S. patent application Ser. No. 16/016,081,
filed Jun. 22, 2018 which is incorporated herein by reference.
FIELD
[0003] The disclosure generally relates to fully differential
adjustable gain devices and methods for use therewith. A fully
differential adjustable gain device can be, e.g., fully
differential filter, a fully differential variable gain amplifier,
a fully differential mixer, or a fully differential
analog-to-digital converter, but is not limited thereto. This
disclosure also relates to receivers that include one or more fully
differential adjustable gain devices.
BACKGROUND
[0004] Receivers included in user equipment (UE) or base stations
(BSs) of wireless networks often include filters and variable gain
amplifiers that are fully differential circuits. Such fully
differential devices typically include both active components, such
as fully differential operational amplifiers (op-amps), as well as
passive components, such as resistors and/or capacitors. It is
often beneficial or otherwise desirable for such fully differential
devices to have adjustable gains, with well controlled gain steps.
However, the input impedance and the frequency response of a fully
differential device is typically changed whenever the gain of the
fully differential circuit is adjusted, which is undesirable.
BRIEF SUMMARY
[0005] According to one aspect of the present disclosure, there is
provided a fully differential adjustable gain device comprising
fully differential input terminals, fully differential output
terminals, fully differential signal processing circuitry, and
first and second cross coupled segments. The differential input
terminals of the fully differential adjustable gain device include
a negative (-) input terminal and a positive (+) input terminal.
The differential output terminals of the fully differential
adjustable gain device include a positive (+) output terminal and a
negative (-) output terminal. The fully differential signal
processing circuitry include differential inputs and differential
outputs, the differential inputs including a negative (-) input and
a positive (+) input, and the differential outputs including a
positive (+) output and a negative (-) output. The positive (+)
output of the fully differential signal processing circuitry
provides the positive (+) output terminal of the fully differential
adjustable gain device. The negative (-) output of the fully
differential signal processing circuitry provides the negative (-)
output terminal of the fully differential adjustable gain device.
The first cross-coupled segment is coupled between the differential
input terminals of the fully differential adjustable gain device
and the negative (-) input of the fully differential signal
processing circuitry. The second cross-coupled segment is coupled
between the differential input terminals of the fully differential
adjustable gain device and the positive (+) input of the fully
differential signal processing circuitry. The fully differential
adjustable gain device has a gain that is adjustable by adjusting
one or more component values of the first and second cross-coupled
segments, while maintaining a substantially consistent frequency
response and a substantially consistent input impedance of the
fully differential adjustable gain device, so long as a specified
relationship between the component values of the first and second
cross-coupled segments is kept substantially constant.
[0006] Optionally, in any of the preceding aspects, the first
cross-coupled segment includes a first passive component having a
first adjustable component value and a second passive component
having a second adjustable component value, the first passive
component coupled between the negative (-) input terminal of the
fully differential adjustable gain device and the negative (-)
input of the fully differential signal processing circuitry, and
the second passive component coupled between the positive (+) input
terminal of the fully differential adjustable gain device and the
negative (-) input of the fully differential signal processing
circuitry. The second cross-coupled segment includes a third
passive component having the first adjustable component value and a
fourth passive component having the second adjustable component
value, the third passive component coupled between the positive (+)
input terminal of the fully differential adjustable gain device and
the positive (+) input of the fully differential signal processing
circuitry, and the fourth passive component coupled between the
negative (-) input terminal of the fully differential adjustable
gain device and the positive (+) input of the fully differential
signal processing circuitry.
[0007] Optionally, in any of the preceding aspects, the first
passive component of the first cross-coupled segment is a first
impedance component having a first adjustable impedance value
(Z1a), the second passive component of the first cross-coupled
segment is a second impedance component having a second adjustable
impedance value (Z1b), the third passive component of the second
cross-coupled segment is a third impedance component having the
first adjustable impedance value (Z1a), and the fourth passive
component of the second cross-coupled segment is a fourth impedance
component having the second adjustable impedance value (Z1b). The
gain of the fully differential adjustable gain device is adjustable
by adjusting the first adjustable impedance value (Z1a) of each of
the first impedance component of the first cross-coupled segment
and the third impedance component of the second cross-coupled
segment, and adjusting the second adjustable impedance value (Z1b)
of each of the second impedance component of the first
cross-coupled segment and the fourth impedance component of the
second cross-coupled segment. The specified relationship between
the component values of the first and second cross-coupled segments
that is kept substantially constant comprises:
Z 1 a ( s ) * Z 1 b ( s ) Z 1 a ( s ) + Z 1 b ( s )
##EQU00001##
[0008] for each value of s, wherein s is a variable that represents
complex frequency.
[0009] Optionally, in any of the preceding aspects, the first
impedance component is a first resistor component having a first
adjustable resistance value (R1a), and thus, the first adjustable
impedance value (Z1a) of the first impedance component is equal to
R1a; the second impedance component is a second resistor component
having a second adjustable resistance value (R1b), and thus, the
second adjustable impedance value (Z1b) of the second impedance
component is equal to Rib; the third impedance component is a third
resistor component having the first adjustable resistance value
(R1a), and thus, the first adjustable impedance value (Z1a) of the
third impedance component is equal to R1a; and the fourth impedance
component is a fourth resistor component having the second
adjustable resistance value (R1b), and thus, the second adjustable
impedance value (Z1b) of the fourth impedance component is equal to
R1b. The gain of the fully differential adjustable gain device is
adjustable by adjusting the first adjustable resistance value (R1a)
of each of the first resistor component of the first cross-coupled
segment and the third resistor component of the second
cross-coupled segment, and adjusting the second adjustable
resistance value (R1b) of each of the second resistor component of
the first cross-coupled segment and the fourth resistor component
of the second cross-coupled segment. The specified relationship
between the component values of the first and second cross-coupled
segments that is kept substantially constant comprises:
R 1 a * R 1 b R 1 a + R 1 b . ##EQU00002##
[0010] Optionally, in any of the preceding aspects, the first
impedance component is a first capacitor component having a first
adjustable capacitance value (C1a), and thus, the first adjustable
impedance value (Z1a) of the first impedance component is equal to
1/(s*C1a); the second impedance component is a second capacitor
component having a second adjustable capacitance value (C1b), and
thus, the second adjustable impedance value (Z1b) of the second
impedance component is equal to 1/(s*C1b); the third impedance
component is a third capacitor component having the first
adjustable capacitance value (C1a), and thus, the first adjustable
impedance value (Z1a) of the third impedance component is equal to
1/(s*C1a); and the fourth impedance component is a fourth capacitor
component having the second adjustable capacitance value (C1b), and
thus, the second adjustable impedance value (Z1b) of the fourth
impedance component is equal to 1/(s*C1b). The gain of the fully
differential adjustable gain device is adjustable by adjusting the
first adjustable capacitor value (C1a) of each of the first
capacitance component of the first cross-coupled segment and the
third capacitor component of the second cross-coupled segment, and
adjusting the second adjustable capacitance value (C1b) of each of
the second capacitor component of the first cross-coupled segment
and the fourth capacitor component of the second cross-coupled
segment. The specified relationship between the component values of
the first and second cross-coupled segments that is kept
substantially constant comprises:
C1a+C1b.
[0011] Optionally, in any of the preceding aspects, the first
impedance component is a first inductor component having a first
adjustable inductance value (L1a), and thus, the first adjustable
impedance value (Z1a) of the first impedance component is equal to
(s*L1a); the second impedance component is a second inductor
component having a second adjustable inductance value (L1 b), and
thus, the second adjustable impedance value (Z1b) of the second
impedance component is equal to (s*L1b); the third impedance
component is a third inductor component having the first adjustable
inductance value (L1a), and thus, the first adjustable impedance
value (Z1a) of the third impedance component is equal to (s*L1a);
and the fourth impedance component is a fourth inductor component
having the second adjustable inductance value (L1 b), and thus, the
second adjustable impedance value (Z1b) of the fourth impedance
component is equal to (s*L1 b). The gain of the fully differential
adjustable gain device is adjustable by adjusting the first
adjustable inductor value (L1a) of each of the first inductor
component of the first cross-coupled segment and the third inductor
component of the second cross-coupled segment, and adjusting the
second adjustable inductance value (L1b) of each of the second
inductor component of the first cross-coupled segment and the
fourth inductor component of the second cross-coupled segment. The
specified relationship between the component values of the first
and second cross-coupled segments that is kept substantially
constant comprises:
( L 1 a * L 1 b ) L 1 a + L 1 b . ##EQU00003##
[0012] Optionally, in any of the preceding aspects, the fully
differential adjustable gain device comprises a fully differential
filter. Optionally, in any of the preceding aspects, the fully
differential filter comprises a multi-feedback (MFB) fully
differential filter, wherein the fully differential signal
processing circuitry thereof includes a fully differential
operational-amplifier (Op-Amp), a pair of feedback resistor
components, and a pair of feedback capacitor components.
[0013] Optionally, in any of the preceding aspects, the fully
differential adjustable gain device comprises a fully differential
variable gain amplifier (VGA), wherein the fully differential
signal processing circuitry thereof includes a fully differential
operational-amplifier (Op-Amp), a pair of feedback resistor
components and a pair of feedback capacitor components.
[0014] Optionally, in any of the preceding aspects, the fully
differential adjustable gain device comprises a fully differential
continuous-time input sigma-delta analog-to-digital converter
(ADC), or a fully differential mixer configured to perform at least
one of frequency down-conversion or frequency up-conversion.
[0015] According to one other aspect of the present disclosure, a
method is for use with a fully differential adjustable gain device,
wherein the fully differential adjustable gain device includes:
differential input terminals of the fully differential adjustable
gain device including a negative (-) input terminal and a positive
(+) input terminal; differential output terminals of the fully
differential adjustable gain device including a positive (+) output
terminal and a negative (-) output terminal; fully differential
signal processing circuitry including differential inputs and
differential outputs, the differential inputs including a negative
(-) input and a positive (+) input, the differential outputs
including a positive (+) output and a negative (-) output; the
positive (+) output of the fully differential signal processing
circuitry providing the positive (+) output terminal of the fully
differential adjustable gain device; and the negative (-) output of
the fully differential signal processing circuitry providing the
negative (-) output terminal of the fully differential adjustable
gain device. The method comprises coupling a first cross-coupled
segment between the differential input terminals of the fully
differential adjustable gain device and the negative (-) input of
the fully differential signal processing circuitry, and coupling a
second cross-coupled segment between the differential input
terminals of the fully differential adjustable gain device and the
positive (+) input of the fully differential signal processing
circuitry. The method also includes adjusting a gain of the fully
differential adjustable gain device, while maintaining a
substantially consistent frequency response and a substantially
consistent input impedance of the fully differential adjustable
gain device, by adjusting one or more component values of the first
and second cross-coupled segments while keeping substantially
constant a specified relationship between the component values of
the first and second cross-coupled segments.
[0016] Optionally, in any of the preceding aspects, the first
cross-coupled segment includes a first passive component having a
first adjustable component value and a second passive component
having a second adjustable component value, the first passive
component coupled between the negative (-) input terminal of the
fully differential adjustable gain device and the negative (-)
input of the fully differential signal processing circuitry, and
the second passive component coupled between the positive (+) input
terminal of the fully differential adjustable gain device and the
negative (-) input of the fully differential signal processing
circuitry. The second cross-coupled segment includes a third
passive component having the first adjustable component value and a
fourth passive component having the second adjustable component
value, the third passive component coupled between the positive (+)
input terminal of the fully differential adjustable gain device and
the positive (+) input of the fully differential signal processing
circuitry, and the fourth passive component coupled between the
negative (-) input terminal of the fully differential adjustable
gain device and the positive (+) input of the fully differential
signal processing circuitry. The adjusting the gain of the fully
differential adjustable gain device, while maintaining a
substantially consistent frequency response and a substantially
consistent input impedance of the fully differential adjustable
gain device, comprises adjusting the first adjustable component
value of each of the first passive component of the first
cross-coupled segment and the third passive component of the second
cross-coupled segment, and adjusting the second adjustable
component value of each of the second passive component of the
first cross-coupled segment and the fourth passive component of the
second cross-coupled segment.
[0017] Optionally, in any of the preceding aspects: the first
passive component of the first cross-coupled segment is a first
impedance component having a first adjustable impedance value
(Z1a); the second passive component of the first cross-coupled
segment is a second impedance component having a second adjustable
impedance value (Z1b); the third passive component of the second
cross-coupled segment is a third impedance component having the
first adjustable impedance value (Z1a); and the fourth passive
component of the second cross-coupled segment is a fourth impedance
component having the second adjustable impedance value (Z1b). The
gain of the fully differential adjustable gain device is adjustable
by adjusting the first adjustable impedance value (Z1a) of each of
the first impedance component of the first cross-coupled segment
and the third impedance component of the second cross-coupled
segment, and adjusting the second adjustable impedance value (Z1b)
of each of the second impedance component of the first
cross-coupled segment and the fourth impedance component of the
second cross-coupled segment. The specified relationship between
the component values of the first and second cross-coupled segments
that is kept substantially constant comprises:
Z 1 a ( s ) * Z 1 b ( s ) Z 1 a ( s ) + Z 1 b ( s )
##EQU00004##
[0018] for each value of s, wherein s is a variable that represents
complex frequency.
[0019] Optionally, in any of the preceding aspects, the fully
differential adjustable gain device, for which the method is used
to adjust the gain, is selected from the group consisting of: a
fully differential low pass filter (LPF); a fully differential
bandpass filter (BPF); a fully differential high pass filter (HPF);
or a fully differential variable gain amplifier (VGA).
[0020] Optionally, in any of the preceding aspects, the fully
differential adjustable gain device, for which the method is used
to adjust the gain, comprises a fully differential continuous-time
input sigma-delta analog-to-digital converter (ADC) or a fully
differential mixer.
[0021] According to still one other aspect of the present
disclosure, there is provided a receiver, comprising a low noise
amplifier (LNA), a mixer, and a fully differential adjustable gain
device. The LNA is configured to amplify a radio frequency (RF)
signal. The mixer is downstream of the LNA and configured to
frequency down-convert the RF signal following amplification
thereof by the LNA. The fully differential adjustable gain device
is downstream of the mixer and configured to at least one of filter
and amplify the RF signal following the frequency down-conversion
thereof by the mixer. The fully differential adjustable gain device
includes: differential input terminals of the fully differential
adjustable gain device including a negative (-) input terminal and
a positive (+) input terminal; differential output terminals of the
fully differential adjustable gain device including a positive (+)
output terminal and a negative (-) output terminal; and fully
differential signal processing circuitry including differential
inputs and differential outputs, the differential inputs including
a negative (-) input and a positive (+) input, the differential
outputs including a positive (+) output and a negative (-) output.
The positive (+) output of the fully differential signal processing
circuitry provides the positive (+) output terminal of the fully
differential adjustable gain device. The negative (-) output of the
fully differential signal processing circuitry provides the
negative (-) output terminal of the fully differential adjustable
gain device. The fully differential adjustable gain device also
includes: a first cross-coupled segment coupled between the
differential input terminals of the fully differential adjustable
gain device and the negative (-) input of the fully differential
signal processing circuitry; and a second cross-coupled segment
coupled between the differential input terminals of the fully
differential adjustable gain device and the positive (+) input of
the fully differential signal processing circuitry. The fully
differential adjustable gain device has a gain that is adjustable
by adjusting one or more component values of the first and second
cross-coupled segments, while maintaining a substantially
consistent frequency response and a substantially consistent input
impedance of the fully differential adjustable gain device, so long
as a specified relationship between the component values of the
first and second cross-coupled segments is kept substantially
constant.
[0022] Optionally, in any of the preceding aspects, the first
cross-coupled segment of the fully differential adjustable gain
device includes a first passive component having a first adjustable
component value and a second passive component having a second
adjustable component value, the first passive component coupled
between the negative (-) input terminal of the fully differential
adjustable gain device and the negative (-) input of the fully
differential signal processing circuitry, and the second passive
component coupled between the positive (+) input terminal of the
fully differential adjustable gain device and the negative (-)
input of the fully differential signal processing circuitry. The
second cross-coupled segment of the fully differential adjustable
gain device includes a third passive component having the first
adjustable component value and a fourth passive component having
the second adjustable component value, the third passive component
coupled between the positive (+) input terminal of the fully
differential adjustable gain device and the positive (+) input of
the fully differential signal processing circuitry, and the fourth
passive component coupled between the negative (-) input terminal
of the fully differential adjustable gain device and the positive
(+) input of the fully differential signal processing
circuitry.
[0023] Optionally, in any of the preceding aspects: the first
passive component of the first cross-coupled segment of the fully
differential adjustable gain device is a first impedance component
having a first adjustable impedance value (Z1a); the second passive
component of the first cross-coupled segment of the fully
differential adjustable gain device is a second impedance component
having a second adjustable impedance value (Z1b); the third passive
component of the second cross-coupled segment of the fully
differential adjustable gain device is a third impedance component
having the first adjustable impedance value (Z1a); and the fourth
passive component of the second cross-coupled segment of the fully
differential adjustable gain device is a fourth impedance component
having the second adjustable impedance value (Z1b). The gain of the
fully differential adjustable gain device is adjustable by
adjusting the first adjustable impedance value (Z1a) of each of the
first impedance component of the first cross-coupled segment and
the third impedance component of the second cross-coupled segment,
and adjusting the second adjustable impedance value (Z1b) of each
of the second impedance component of the first cross-coupled
segment and the fourth impedance component of the second
cross-coupled segment. The specified relationship between the
component values of the first and second cross-coupled segments
that is kept substantially constant comprises:
Z 1 a ( s ) * Z 1 b ( s ) Z 1 a ( s ) + Z 1 b ( s )
##EQU00005##
[0024] for each value of s, wherein s is a variable that represents
complex frequency.
[0025] Optionally, in any of the preceding aspects, the fully
differential adjustable gain device, which is downstream of the
mixer and is configured to at least one of filter and amplify the
RF signal following the frequency down-conversion thereof by the
mixer, is selected from the group consisting of: a fully
differential low pass filter (LPF); a fully differential bandpass
filter (BPF); a fully differential high pass filter (HPF); or a
fully differential variable gain amplifier (VGA).
[0026] Optionally, in any of the preceding aspects, the receiver is
included in user equipment or a base station that is configured to
communicate data within a wireless network.
[0027] This Summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This Summary is not intended to identify
key features or essential features of the claimed subject matter,
nor is it intended to be used as an aid in determining the scope of
the claimed subject matter. The claimed subject matter is not
limited to implementations that solve any or all disadvantages
noted in the Background.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Aspects of the present disclosure are illustrated by way of
example and are not limited by the accompanying figures for which
like references indicate like elements.
[0029] FIG. 1 illustrates an exemplary wireless network for
communicating data.
[0030] FIG. 2 illustrates exemplary details of an instance of user
equipment (UE) introduced in FIG. 1.
[0031] FIG. 3 illustrates exemplary details of an instance of a
base station (BS) introduced in FIG. 1.
[0032] FIG. 4 illustrates exemplary details of a receiver included
in UE or a BS shown in FIGS. 2 and 3.
[0033] FIG. 5 illustrates a prior art fully differential
multi-feedback (MFB) low pass filter (LPF) that can be included in
a receiver, such as the receiver illustrated in FIG. 4.
[0034] FIG. 6 illustrates a fully differential adjustable gain MFB
LPF, according to an embodiment of the present technology, which
fully differential adjustable gain MFB LPF filter can be included
in a receiver, such as the receiver illustrated in FIG. 4, but is
not limited thereto.
[0035] FIG. 7 illustrates a fully differential adjustable gain MFB
bandpass filter (BPF), according to an embodiment of the present
technology.
[0036] FIG. 8 illustrates a fully differential adjustable gain MFB
high pass filter (HPF), according to an embodiment of the present
technology.
[0037] FIG. 9 illustrates a fully differential variable gain
amplifier (VGA), according to an embodiment of the present
technology, which fully differential VGA can be included in a
receiver, such as the receiver illustrated in FIG. 4, but is not
limited thereto.
[0038] FIG. 10 illustrates a fully differential adjustable gain
device having cross-coupled segments that include resistor
components, according to an embodiment of the present
technology.
[0039] FIG. 11 illustrates a fully differential adjustable gain
device having cross-coupled segments that include impedance
components, according to an embodiment of the present
technology.
[0040] FIG. 12 illustrates a fully differential adjustable gain
device having cross-coupled segments that include capacitor
components, according to an embodiment of the present
technology.
[0041] FIG. 13 illustrates a fully differential adjustable gain
device having cross-coupled segments that include inductor
components, according to an embodiment of the present
technology.
[0042] FIG. 14 is a high-level flow diagram that is used to
summarize methods according to various embodiments of the present
technology.
DETAILED DESCRIPTION
[0043] The present disclosure will now be described with reference
to the figures, which in general relate to fully differential
adjustable gain devices, and methods for use therewith. The present
disclosure also relates to receivers that include such fully
differential adjustable gain devices, wherein the receivers can be
used within wireless networks, an example of which is described
below with reference to FIG. 1. A fully differential adjustable
gain device can be, e.g., a fully differential filter, a fully
differential variable gain amplifier (VGA), a fully differential
continuous-time input sigma-delta analog-to-digital converter
(ADC), or a fully differential mixer, but is not limited thereto.
The term "device" as used herein can refer to a chip, a sub-circuit
of a larger circuit included in a chip, a sub-circuit of a larger
circuit included on a printed circuit board (PCB), or more
generally, can be used to refer to a circuit.
[0044] In accordance with certain embodiments of the present
technology, a fully differential adjustable gain device described
herein includes differential input terminals, differential output
terminals, fully differential signal processing circuitry, and
first and second cross-coupled segments. The differential input
terminals of the fully differential adjustable gain device include
a negative (-) input terminal and a positive (+) input terminal.
The differential output terminals of the fully differential
adjustable gain device include a positive (+) output terminal and a
negative (-) output terminal. The fully differential signal
processing circuitry includes differential inputs and differential
outputs, with the differential inputs including a negative (-)
input and a positive (+) input, and the differential outputs
including a positive (+) output and a negative (-) output. The
positive (+) output of the fully differential signal processing
circuitry provides the positive (+) output terminal of the fully
differential adjustable gain device. The negative (-) output of the
fully differential signal processing circuitry provides the
negative (-) output terminal of the fully differential adjustable
gain device. The first cross-coupled segment is coupled between the
differential input terminals of the fully differential adjustable
gain device and the negative (-) input of the fully differential
signal processing circuitry. The second cross-coupled segment is
coupled between the differential input terminals of the fully
differential adjustable gain device and the positive (+) input of
the fully differential signal processing circuitry. The fully
differential adjustable gain device has a gain that is adjustable
by adjusting one or more component values of the first and second
cross-coupled segments, while maintaining a substantially
consistent frequency response and a substantially consistent input
impedance of the fully differential adjustable gain device, so long
as a specified relationship between the component values of the
first and second cross-coupled segments is kept substantially
constant. As will be described in additional detail below, the
fully differential signal processing circuitry (of the fully
differential adjustable gain device) can include a fully
differential operational-amplifier (Op-Amp), a pair of feedback
resistor components, and a pair of feedback capacitor components,
which can be arranged such that the fully differential adjustable
gain device operates as a low pass filter (LPF), a bandpass filter
(BPF), a high pass filter (HPF), or a variable gain amplifier
(VGA), but is not limited thereto.
[0045] It is understood that the present embodiments of the
disclosure may be implemented in many different forms and that
claims scopes should not be construed as being limited to the
embodiments set forth herein. Rather, these embodiments are
provided so that this disclosure will be thorough and complete and
will fully convey the inventive embodiment concepts to those
skilled in the art. Indeed, the disclosure is intended to cover
alternatives, modifications and equivalents of these embodiments,
which are included within the scope and spirit of the disclosure as
defined by the appended claims. Furthermore, in the following
detailed description of the present embodiments of the disclosure,
numerous specific details are set forth in order to provide a
thorough understanding. However, it will be clear to those of
ordinary skill in the art that the present embodiments of the
disclosure may be practiced without such specific details.
[0046] Before provided additional details of fully differential
adjustable gain devices of embodiments of the present technology,
FIG. 1 is used to describe an exemplary wireless network for
communicating data, FIG. 2 is used to describe exemplary details of
an instance of user equipment (UE) introduced in FIG. 1, and FIG. 3
is used to describe exemplary details of an instance of a base
station (BS) introduced in FIG. 1. Additionally, FIG. 4 is used to
describe exemplary details of a receiver included UE or a BS. The
fully differential adjustable gain circuits described herein can be
included within a receiver, such as the receiver described with
reference to FIG. 4, but is not limited thereto.
[0047] Referring to FIG. 1, illustrated therein is an exemplary
wireless network for communicating data. The communication system
100 includes, for example, user equipment 110A, 110B, and 110C,
radio access networks (RANs) 120A and 120B, a core network 130, a
public switched telephone network (PSTN) 140, the Internet 150, and
other networks 160. Additional or alternative networks include
private and public data-packet networks including corporate
intranets. While certain numbers of these components or elements
are shown in the figure, any number of these components or elements
may be included in the system 100.
[0048] In one embodiment, the wireless network may be a fifth
generation (5G) network including at least one 5G base station
which employs orthogonal frequency-division multiplexing (OFDM)
and/or non-OFDM and a transmission time interval (TTI) shorter than
1 milliseconds (e.g. 100 or 200 microseconds), to communicate with
the communication devices. In general, a base station may also be
used to refer any of the eNB and the 5G BS (gNB). In addition, the
network may further include a network server for processing
information received from the communication devices via the at
least one eNB or gNB.
[0049] System 100 enables multiple wireless users to transmit and
receive data and other content. The system 100 may implement one or
more channel access methods, such as but not limited to code
division multiple access (CDMA), time division multiple access
(TDMA), frequency division multiple access (FDMA), orthogonal FDMA
(OFDMA), or single-carrier FDMA (SC-FDMA).
[0050] The user equipment (UE) 110A, 110B, and 110C, which can be
referred to individually as an UE 110, or collectively as the UEs
110, are configured to operate and/or communicate in the system
100. For example, an UE 110 can be configured to transmit and/or
receive wireless signals or wired signals. Each UE 110 represents
any suitable end user device and may include such devices (or may
be referred to) as a user equipment/device, wireless
transmit/receive unit (UE), mobile station, fixed or mobile
subscriber unit, pager, cellular telephone, personal digital
assistant (PDA), smartphone, laptop, computer, touchpad, wireless
sensor, wearable devices or consumer electronics device.
[0051] In the depicted embodiment, the RANs 120A, 120B include one
or more base stations (BSs) 170A, 170B, respectively. The RANs 120A
and 120B can be referred to individually as a RAN 120, or
collectively as the RANs 120. Similarly, the base stations (BSs)
170A and 170B can be referred to individually as a base station
(BS) 170, or collectively as the base stations (BSs) 170. Each of
the BSs 170 is configured to wirelessly interface with one or more
of the UEs 110 to enable access to the core network 130, the PSTN
140, the Internet 150, and/or the other networks 160. For example,
the base stations (BSs) 170 may include one or more of several
well-known devices, such as a base transceiver station (BTS), a
Node-B (NodeB), an evolved NodeB (eNB), a next (fifth) generation
(5G) NodeB (gNB), a Home NodeB, a Home eNodeB, a site controller,
an access point (AP), or a wireless router, or a server, router,
switch, or other processing entity with a wired or wireless
network.
[0052] In one embodiment, the BS 170A forms part of the RAN 120A,
which may include one or more other BSs 170, elements, and/or
devices. Similarly, the BS 170B forms part of the RAN 120B, which
may include one or more other BSs 170, elements, and/or devices.
Each of the BSs 170 operates to transmit and/or receive wireless
signals within a particular geographic region or area, sometimes
referred to as a "cell." In some embodiments, multiple-input
multiple-output (MIMO) technology may be employed having multiple
transceivers for each cell.
[0053] The BSs 170 communicate with one or more of the UEs 110 over
one or more air interfaces (not shown) using wireless communication
links. The air interfaces may utilize any suitable radio access
technology.
[0054] It is contemplated that the system 100 may use multiple
channel access functionality, including for example schemes in
which the BSs 170 and UEs 110 are configured to implement the Long
Term Evolution wireless communication standard (LTE), LTE Advanced
(LTE-A), and/or LTE Multimedia Broadcast Multicast Service (MBMS).
In other embodiments, the base stations 170 and user equipment
110A-110C are configured to implement UMTS, HSPA, or HSPA+
standards and protocols. Of course, other multiple access schemes
and wireless protocols may be utilized.
[0055] The RANs 120 are in communication with the core network 130
to provide the UEs 110 with voice, data, application, Voice over
Internet Protocol (VoIP), or other services. As appreciated, the
RANs 120 and/or the core network 130 may be in direct or indirect
communication with one or more other RANs (not shown). The core
network 130 may also serve as a gateway access for other networks
(such as PSTN 140, Internet 150, and other networks 160). In
addition, some or all of the UEs 110 may include functionality for
communicating with different wireless networks over different
wireless links using different wireless technologies and/or
protocols.
[0056] The RANs 120 may also include millimeter and/or microwave
access points (APs). The APs may be part of the BSs 170 or may be
located remote from the BSs 170. The APs may include, but are not
limited to, a connection point (an mmW CP) or a BS 170 capable of
mmW communication (e.g., a mmW base station). The mmW APs may
transmit and receive signals in a frequency range, for example,
from 24 GHz to 100 GHz, but are not required to operate throughout
this range. As used herein, the term base station is used to refer
to a base station and/or a wireless access point.
[0057] Although FIG. 1 illustrates one example of a communication
system, various changes may be made to FIG. 1. For example, the
communication system 100 could include any number of user
equipment, base stations, networks, or other components in any
suitable configuration. It is also appreciated that the term user
equipment may refer to any type of wireless device communicating
with a radio network node in a cellular or mobile communication
system. Non-limiting examples of user equipment are a target
device, device-to-device (D2D) user equipment, machine type user
equipment or user equipment capable of machine-to-machine (M2M)
communication, laptops, PDA, iPad, Tablet, mobile terminals, smart
phones, laptop embedded equipped (LEE), laptop mounted equipment
(LME) and USB dongles.
[0058] FIG. 2 illustrates example details of an UE 110 that may
implement the methods and teachings according to this disclosure.
The UE 110 may for example be a mobile telephone, but may be other
devices in further examples such as a desktop computer, laptop
computer, tablet, hand-held computing device, automobile computing
device and/or other computing devices. As shown in the figure, the
exemplary UE 110 is shown as including at least one transmitter
202, at least one receiver 204, memory 206, at least one processor
208, and at least one input/output device 212. The processor 208
can implement various processing operations of the UE 110. For
example, the processor 208 can perform signal coding, data
processing, power control, input/output processing, or any other
functionality enabling the UE 110 to operate in the system 100
(FIG. 1). The processor 208 may include any suitable processing or
computing device configured to perform one or more operations. For
example, the processor 208 may include a microprocessor,
microcontroller, digital signal processor, field programmable gate
array, or application specific integrated circuit.
[0059] The transmitter 202 can be configured to modulate data or
other content for transmission by at least one antenna 210. The
transmitter 202 can also be configured to amplify, filter and
frequency convert RF signals before such signals are provided to
the antenna 210 for transmission. The transmitter 202 can include
any suitable structure for generating signals for wireless
transmission.
[0060] The receiver 204 can be configured to demodulate data or
other content received by the at least one antenna 210. The
receiver 204 can also be configured to amplify, filter and
frequency convert RF signals received via the antenna 210. The
receiver 204 can include any suitable structure for processing
signals received wirelessly. The antenna 210 can include any
suitable structure for transmitting and/or receiving wireless
signals. The same antenna 210 can be used for both transmitting and
receiving RF signals, or alternatively, different antennas 210 can
be used for transmitting signals and receiving signals.
[0061] It is appreciated that one or multiple transmitters 202
could be used in the UE 110, one or multiple receivers 204 could be
used in the UE 110, and one or multiple antennas 210 could be used
in the UE 110. Although shown as separate blocks or components, at
least one transmitter 202 and at least one receiver 204 could be
combined into a transceiver. Accordingly, rather than showing a
separate block for the transmitter 202 and a separate block for the
receiver 204 in FIG. 2, a single block for a transceiver could have
been shown.
[0062] The UE 110 further includes one or more input/output devices
212. The input/output devices 212 facilitate interaction with a
user. Each input/output device 212 includes any suitable structure
for providing information to or receiving information from a user,
such as a speaker, microphone, keypad, keyboard, display, or touch
screen.
[0063] In addition, the UE 110 includes at least one memory 206.
The memory 206 stores instructions and data used, generated, or
collected by the UE 110. For example, the memory 206 could store
software or firmware instructions executed by the processor(s) 204
and data used to reduce or eliminate interference in incoming
signals. Each memory 206 includes any suitable volatile and/or
non-volatile storage and retrieval device(s). Any suitable type of
memory may be used, such as random access memory (RAM), read only
memory (ROM), hard disk, optical disc, subscriber identity module
(SIM) card, memory stick, secure digital (SD) memory card, and the
like.
[0064] FIG. 3 illustrates an example BS 170 that may implement the
methods and teachings according to this disclosure. As shown in the
figure, the BS 170 includes at least one processor 308, at least
one transmitter 302, at least one receiver 304, one or more
antennas 310, and at least one memory 306. The processor 308
implements various processing operations of the BS 170, such as
signal coding, data processing, power control, input/output
processing, or any other functionality. Each processor 308 includes
any suitable processing or computing device configured to perform
one or more operations. Each processor 308 could, for example,
include a microprocessor, microcontroller, digital signal
processor, field programmable gate array, or application specific
integrated circuit.
[0065] Each transmitter 302 includes any suitable structure for
generating signals for wireless transmission to one or more UEs 110
or other devices. Each receiver 304 includes any suitable structure
for processing signals received wirelessly from one or more UEs 110
or other devices. Although shown as separate blocks or components,
at least one transmitter 302 and at least one receiver 304 could be
combined into a transceiver. Each antenna 310 includes any suitable
structure for transmitting and/or receiving wireless signals. While
a common antenna 310 is shown here as being coupled to both the
transmitter 302 and the receiver 304, one or more antennas 310
could be coupled to the transmitter(s) 302, and one or more
separate antennas 310 could be coupled to the receiver(s) 304. Each
memory 306 includes any suitable volatile and/or non-volatile
storage and retrieval device(s).
[0066] Certain embodiments of the present technology described
herein can be implemented using hardware, software, or a
combination of both hardware and software. The software used is
stored on one or more of the processor readable storage devices
described above to program one or more of the processors to perform
the functions described herein. The processor readable storage
devices can include computer readable media such as volatile and
non-volatile media, removable and non-removable media. By way of
example, and not limitation, computer readable media may comprise
computer readable storage media and communication media. Computer
readable storage media may be implemented in any method or
technology for storage of information such as computer readable
instructions, data structures, program modules or other data.
Examples of computer readable storage media include RAM, ROM,
EEPROM, flash memory or other memory technology, CD-ROM, digital
versatile disks (DVD) or other optical disk storage, magnetic
cassettes, magnetic tape, magnetic disk storage or other magnetic
storage devices, or any other medium which can be used to store the
desired information and which can be accessed by a computer. A
computer readable medium or media does (do) not include propagated,
modulated or transitory signals.
[0067] Communication media typically embodies computer readable
instructions, data structures, program modules or other data in a
propagated, modulated or transitory data signal such as a carrier
wave or other transport mechanism and includes any information
delivery media. The term "modulated data signal" means a signal
that has one or more of its characteristics set or changed in such
a manner as to encode information in the signal. By way of example,
and not limitation, communication media includes wired media such
as a wired network or direct-wired connection, and wireless media
such as RF and other wireless media. Combinations of any of the
above are also included within the scope of computer readable
media.
[0068] In alternative embodiments, some or all of the software can
be replaced by dedicated hardware logic components. For example,
and without limitation, illustrative types of hardware logic
components that can be used include Field-programmable Gate Arrays
(FPGAs), Application-specific Integrated Circuits (ASICs),
Application-specific Standard Products (ASSPs), System-on-a-chip
systems (SOCs), Complex Programmable Logic Devices (CPLDs), special
purpose computers, etc. In one embodiment, software (stored on a
storage device) implementing one or more embodiments is used to
program one or more processors. The one or more processors can be
in communication with one or more computer readable media/storage
devices, peripherals and/or communication interfaces.
[0069] FIG. 4 illustrates exemplary details of a receiver 404,
which can be the receiver 204 included in the UE 110 (shown in FIG.
2) or the receiver 304 included in the BS 170 (shown in FIG. 3),
but is not limited thereto. Referring to FIG. 4, the receiver 404
is shown as including an input 406 at which is received a radio
frequency (RF) signal, and thus, the input 406 can also be referred
to as the RF input 406. The RF input 406 can be coupled to an
antenna or a coupler, but is not limited thereto. The RF signal
received by the RF input 406 is provided to a low noise amplifier
(LNA) 408, which may have an adjustable gain. The LNA 408 amplifies
the relatively low-power RF signal it receives without
significantly degrading the signal's signal-to-noise ratio (SNR).
The amplified RF signal that is output by the LNA 408 is provided
to a mixer 410. The mixer 410, in addition to receiving the
amplified RF signal from the LNA 408, also receives an oscillator
signal (e.g., from a local oscillator, not shown), and adjusts the
frequency of the amplifier RF signal, e.g., from first frequency to
a second frequency that is lower than the first frequency. More
specifically, the mixer 410 can be a down-mixer (DN MIX) that
frequency down-converts the amplified RF signal from a relatively
high frequency to a baseband frequency, or an intermediate
frequency (IF) that is offset from the baseband frequency.
[0070] Still referring to FIG. 4, the frequency down-converted RF
signal that is output from the mixer 410 is shown as being provided
to a trans-impedance amplifier (TIA) 412. The TIA 412 acts as a
current buffer to isolate a multi-feedback (MFB) filter 414 that is
downstream of the TIA 412, from the mixer 410 that is upstream of
the TIA 412. The MFB filter 414 low pass filters the frequency
down-converted RF signal, to filter out high frequency signal
components that are not of interest, such as HF noise. The filtered
signal that is output from the MFB filter 414 is provided to a
variable gain amplifier (VGA), which is used to amplify the signal
before it is provided to an analog-to-digital converter (A/D) 418,
which converts the signal from an analog signal to a digital
signal. The digital signal output from the A/D 418 is then provided
to a digital filter 420, which performs additional filtering to
remove out of band signal components and attenuates quantization
energy from the A/D 418. The filtered digital signal that is output
by the digital filter 420 is then provided to further digital
circuitry that is downstream from the digital filter 420. Such
further digital circuitry can include, for example, a digital
signal processor (DSP), but is not limited thereto. The same DSP,
or a different DSP, can be used to implement the digital filter
420.
[0071] In FIG. 4, the TIA 412, the MFB filter 414, and the VGA 416
are illustrated as fully differential circuits, since they each
have respective differential inputs and differential outputs. By
contrast the LNA 408 is illustrated as having a single ended input
and a single ended output, the mixer 410 is illustrated as having a
single ended input and differential outputs, and the A/D 418 is
illustrated as having differential inputs and a single ended
output. However, it is noted that the LNA 408 can alternatively
have a single ended input and differential outputs, or differential
inputs and differential outputs. Similarly, the mixer 410 can
alternatively be a fully differential mixer having differential
inputs and differential outputs, and the A/D 418 can be a fully
differential A/D having differential inputs and differential
outputs. Other variations are also possible and within the scope of
the embodiments described herein.
[0072] FIG. 5 will now be used to describe a prior art fully
differential multi-feedback (MFB) low pass filter (LPF) 502 that
can be included in a receiver, such as the receiver 404 illustrated
in FIG. 4. More specifically, the MFB LPF 502 can be used as the
MFB filter 414 shown in FIG. 4. The fully differential MFB LPF 502,
which can also be referred to herein more succinctly as the MFB
filter 502, is shown as having differential input terminals,
including a negative (-) input terminal 504 and a positive (+)
input terminal 506. The MFB filter 502 is also shown as having
differential output terminals, including a positive (+) output
terminal 508 and a negative (-) output terminal 510. The MFB filter
502 includes a fully differential operational amplifier (op-amp)
518 including differential inputs and differential outputs, wherein
the differential inputs include a negative (-) input 513 and a
positive (+) input 515, and the differential outputs include a
positive (+) output 519 and a negative (-) output 521. Negative
inputs are also known as inverting inputs, and positive inputs are
also known as non-inverting inputs. Similarly, negative outputs are
also known as inverting outputs, and positive outputs are also
known as non-inverting outputs. The MFB LPF filter 502 is a fully
differential filter because it includes both differential inputs
and differential outputs.
[0073] In the MFB filter 502, the positive (+) output 519 of the
op-amp 518 is connected to the negative (-) input 513 of the op-amp
519 by a feedback capacitor component 542 having a capacitance
value Cf. The negative (-) output 521 of the op-amp 518 is
connected to the positive (+) input 515 of the op-amp 518 by a
feedback capacitor component 546 having the same capacitance value
Cf as the feedback capacitor component 542. The MFB filter 502 also
includes feedback resistor components 541 and 545 that each have
the same resistance value Rf. One of the terminals of the feedback
resistor component 541 is connected to the positive (+) output 519
of the op-amp 518, and the other terminal of the feedback resistor
541 is connected to one of the terminals of the capacitor component
548, which has a capacitance value C0/2. One of the terminals of
the feedback resistor component 545 is connected to the negative
(-) output 521 of the op-amp 518, and the other terminal of the
feedback resistor component 545 is connected to the other one of
the terminals of the capacitor component 548. One of the terminals
of a resistor component 543, having a resistance value R0, is
connected to the negative (-) input 513 of the op-amp 518, and the
other one of the terminals of the resistor component 543 is
connected to one of the terminals of the capacitor component 548.
One of the terminals of a resistor component 547, having the
resistance value R0, is connected to the positive (+) input 515 of
the op-amp 518, and the other one of the terminals of the resistor
component 547 is connected to the other one of the terminals of the
capacitor component 548. A resistor component 548, having a
resistance value R1, is coupled between the negative input terminal
504 of the MFB filter 502 and one of the terminals of the capacitor
component 548. A resistor component 526, having the same resistance
value R1 as the resistor component 524, is coupled between the
positive input terminal 506 of the MFB filter 502 and the other one
of the terminals of the capacitor component 548.
[0074] Vo(s)/Vi(s) for the fully differential MFB LPF 502 is shown
in the following Equation(1A):
Vo ( s ) Vi ( s ) = Gain * - 1 C 0 * Cf * R 0 * Rf s 2 + s * 1 C 0
* ( 1 R 0 + 1 R 1 + 1 Rf ) + 1 C 0 * Cf * R 0 * Rf ##EQU00006##
[0075] where, [0076] Vi(s) is the voltage of the differential input
signal, [0077] Vo(s) is the voltage of the differential output
signal, [0078] Gain is equal to Rf/R1, [0079] R0 is the resistance
of each of the resistor components 543 and 547, [0080] R1 is the
resistance of each of the resistor components 524 and 526, [0081]
Rf is the resistance of each of the feedback resistor components
541 and 545, [0082] Cf is the capacitance of each of the feedback
capacitor components 542 and 546, [0083] C0 is twice the
capacitance of the capacitor component 548, and [0084] s is a
variable that represents complex frequency.
[0085] The MFB filter 502 can have a fixed gain, which may or may
not be unity gain, or may have an adjustable gain. Where the MFB
filter 502 has an adjustable gain, it is desirable for the MFB
filter to have substantially the same frequency response across the
different gain settings. However, in order to adjust the gain of
the MFB filter 502 while maintaining the same frequency response
across different gain settings, at least five of the nine passive
components included in the MFB filter 502 need to be adjusted,
including the feedback resistor components 541 and 545, the
feedback capacitor components 542 and 546, and the capacitor
component 548. However, even if these five of the nine passive
components of the MFB filter 502 are adjusted to maintain
substantially the same frequency response for different gain
settings, the input impedance of the MFB filter 502 significantly
changes from one gain setting to another, which is typically
unacceptable.
[0086] In order to adjust the gain of the MFB filter 502, while
maintaining substantially the same (i.e., substantially consistent)
frequency response, as well as substantially the same (i.e.,
substantially consistent) input impedance, would require adjusting
at least six of the nine passive components included in the MFB
filter 502, including the feedback resistor components 541 and 545,
the feedback capacitor components 542 and 546, and the resistor
components 524 and 526. However, the complex circuitry required to
control at least six of the nine passive components would
significantly increase the die area and cost required to provide
the MFB filter 502, particularly if the MFB filter 502 had several
different bandwidth modes. Additionally, the fact that the
relationship between the component values is not linear across the
different gain settings adds to the difficulty of maintaining
substantially the same frequency response, as well as substantially
the same input impedance, across different gain settings.
[0087] A resistor component, as the term is used herein, can
include a single circuit element, such as a single resistor, or
multiple circuit elements or sub-components, such as multiple
resistors connected in a resistor network, but is not limited
thereto. For example, a resistor component having a resistance of 1
kilo-ohm, can be implemented using a single 1 kilo-ohm resistor,
two 500 ohm resistors connected in series, or two 2 kilo-ohm
resistors connected in parallel, but is not limited thereto. A
capacitor component, as the term is used herein, can include a
single circuit element, such as a single capacitor, or multiple
circuit elements or sub-components, such as multiple capacitors
connected in a capacitor network, but is not limited thereto.
Similarly, an inductor component, as the term is used herein, can
include a single circuit element, or multiple circuit elements or
sub-components, such as one or more inductors. Resistors,
capacitors, and inductors are examples of various types of passive
components, each of which can also be referred to as an impedance
component having an impedance value.
[0088] Referring again to FIG. 5, the circuitry within the dashed
lined block labeled 512 can be referred to collectively as fully
differential filter circuitry 512 having differential inputs and
differential outputs, wherein the differential inputs include a
negative (-) input 514 and a positive (+) input 516, and the
differential outputs include a positive (+) output 520 and a
negative (-) output 522. The fully differential filter circuitry
512 can be referred to more generally as fully differential signal
processing circuitry. As can be appreciated from FIG. 5, the
resistor components 524 and 526, which have the same resistance
value R1, are connected between the differential input terminals
504, 506 of the MFB filter 502 and the differential inputs 514, 516
of the fully differential filter circuitry 512.
[0089] In accordance with certain embodiments of the present
technology, initially described below with reference to FIG. 6, the
resistor components 524 and 526 (in FIG. 5) are replaced with two
cross-coupled segments 624 and 626 (as shown in FIG. 6). Benefits
of using the cross-coupled segments 624 and 626 will be described
below.
[0090] Referring to FIG. 6, shown therein is a fully differential
MFB LPF 602, according to an embodiment of the present technology.
The MFB LPF 602 can be included in a receiver, such as the receiver
404 illustrated in FIG. 4, e.g., as the MFB filter 414 shown in
FIG. 4. The fully differential MFB LPF 602, which can also be
referred to herein more succinctly as the MFB filter 602, is shown
as having differential input terminals, including a negative (-)
input terminal 604 and a positive (+) input terminal 606. The MFB
filter 602 is also shown as having differential output terminals,
including a positive (+) output terminal 608 and a negative (-)
output terminal 610. The MFB filter 602 includes a fully
differential op-amp 618 including differential inputs and
differential outputs, wherein the differential inputs include a
negative (-) input 613 and a positive (+) input 615, and the
differential outputs include a positive (+) output 619 and a
negative (-) output 621. The MFB filter 602 is also shown as
including feedback resistor components 641 and 645, having the same
resistance value Rf, which are connected in the same manner as the
resistor components 541 and 545 described above with reference to
FIG. 5. The MFB filter is also shown as including feedback
capacitor components 642 and 646, having the same capacitance value
Cf, which are connected in the same manner as the capacitor
components 542 and 546 described above with reference to FIG. 5.
Similarly, the resistor components 643 and 647, having the same
resistance value R0, are connected in the same manner as the
resistor components 543 and 547 described above with reference to
FIG. 5. Further, the capacitor component 648, having the resistance
value C0/2, is connected in the same manner as the capacitor
component 548 described above with reference to FIG. 5. The MFB LPF
filter 602 is a fully differential filter because it includes both
differential inputs and differential outputs.
[0091] Still referring to FIG. 6, the circuitry within the dashed
lined block labeled 612 can be referred to collectively as fully
differential filter circuitry 612 having differential inputs and
differential outputs, wherein the differential inputs include a
negative (-) input 614 and a positive (+) input 616, and the
differential outputs include a positive (+) output 620 and a
negative (-) output 622. The fully differential filter circuitry
612 can be referred to more generically as fully differential
signal processing circuitry. In FIG. 6, the cross-coupled segment
624 is coupled between the differential input terminals 604, 606 of
the MFB filter 602 and the negative (-) input 614 of the fully
differential filter circuitry 612, wherein the cross-coupled
segment 624 includes a resistor component 623 having a resistance
value R1a, and also includes a resistor component 625 having a
resistance value R1b. The cross-coupled segment 626 is coupled
between the differential input terminals 604, 606 of the MFB filter
602 and the positive (+) input 616 of the fully differential filter
circuitry 612, wherein the cross-coupled segment 626 includes a
resistor component 629 having the resistance value R1a (which is
the same resistance as the resistor component 623), and also
includes a resistor component 627 having the resistance R1b value
(which is the same resistance as the resistor component 625). The
resistor components 623, 625, 627 and 629 are adjustable resistor
components, and thus, each can be said to have an adjustable
resistance. Accordingly, the resistor components 623 and 629 can be
said to have an adjustable resistance value R1a, and the resistor
components 625 and 627 can be said to have an adjustable resistance
value R1b.
[0092] More specifically, as can be appreciated from FIG. 6, the
cross-coupled segment 624 includes the resistor component 623
having the adjustable resistance value R1a and the resistor
component 625 having the adjustable resistance value R1b. The
resistor component 623 is coupled between the negative (-) input
terminal 604 of the MFB filter 602 and the negative (-) input 614
of the fully differential filter circuitry 612. The resistor
component 625 is coupled between the positive (+) input terminal
606 of the MFB filter 602 and the negative (-) input 614 of the
fully differential filter circuitry 612. As can also be appreciated
from FIG. 6, the cross-coupled segment 626 includes the resistor
component 629 having the adjustable resistance value R1a and the
resistor component 627 having the adjustable resistance value R1b.
The resistor component 629 is coupled between the positive (+)
input terminal 606 of the MFB filter 602 and the positive (+) input
616 of the fully differential filter circuitry 612. The resistor
component 627 is coupled between the negative (-) input terminal
604 of the MFB filter 602 and the positive (+) input 616 of the
fully differential filter circuitry 612. The terms "resistance
value" and "resistance" are used interchangeably herein, as are the
terms "capacitance value" and "capacitance", the terms "inductance
value" and "inductance", and the terms "impedance value" and
"impedance".
[0093] Vo(s)/Vi(s) for the fully differential MFB LPF 602 is shown
in the following Equation(1B):
Vo ( s ) Vi ( s ) = Gain * - 1 C 0 * Cf * R 0 * Rf s 2 + s * 1 C 0
* ( 1 R 0 + 1 R 1 + 1 Rf ) + 1 C 0 * Cf * R 0 * Rf ##EQU00007##
[0094] where, [0095] Vi(s) is the voltage of the differential input
signal, [0096] Vo(s) is the voltage of the differential output
signal, [0097] Gain is equal to (Rf/R1b)-(Rf/R1a), [0098] R0 is the
resistance of each of the resistor components 643 and 647, [0099]
R1 is equal to (R1a*R1b)/(R1a+R1b), [0100] R1a is the resistance of
each of the resistor components 623 and 629, [0101] R1b is the
resistance of each of the resistor components 625 and 627, [0102]
Rf is the resistance of each of the feedback resistor components
641 and 645, [0103] Cf is the capacitance of each of the feedback
capacitor components 642 and 646, [0104] C0 is twice the
capacitance of the capacitor component 548, and [0105] s is a
variable that represents complex frequency.
[0106] Beneficially, the gain of the fully differential MFB LPF 602
can be adjusted, without substantially affecting a frequency
response and without substantially affecting an input impedance of
the fully differential MFB LPF 602 (i.e., while keeping the
frequency response substantially consistent and the input impedance
substantially consistent of the fully differential MFB LPF 602), by
only adjusting the resistance R1a (which is the resistance of each
of the resistor component 623 of the cross-coupled segment 624 and
the resistor component 629 of the cross-coupled segment 626), and
adjusting the resistance R1b (which is the resistance of each of
the resistor component 625 of the cross-coupled segment 624 and the
resistor component 627 of the cross-coupled segment 626).
Accordingly, the other seven passive components of the MFB filter
(including the feedback resistor components 641 and 645, the
feedback capacitor components 642 and 646, the resistor components
643 and 647, and the capacitive component 648) need not be adjusted
and can have fixed component values. The described embodiment
enables the MFB filter 602 to be implemented in a relatively small
die area, with relatively easy gain control. The condition that
needs to be met, to keep the frequency response substantially
consistent and the input impedance substantially consistent of the
fully differential MFB LPF 602, is keeping substantially constant a
specified relationship between component values of the
cross-coupled segments 624 and 626. The input impedance and
frequency response of the fully differential MFB LPF 602 is the
same as the input impedance and frequency response of the fully
differential MFB LPF 502 (discussed above with reference to FIG.
5), with R1 in equaling (R1a*R1b)/(R1a+R1b), which equation is
referred to as Equation(2) below. More specifically, the gain of
the MFB filter 602 can be adjusted, while keeping the frequency
response of MFB filter 602 substantially consistent and keeping the
input impedance of the MFB filter 602 substantially consistent, by
adjusting a value of the adjustable resistance R1a and a value of
adjustable resistance R1b, which are resistance values of resistor
components included in each of the cross-coupled segments 624 and
626, while keeping substantially constant the following
Equation(2):
R 1 a * R 1 b R 1 a + R 1 b . ##EQU00008##
[0107] For a specific example, assume that four desired gain
settings include gains of 14.00 dB, 10.00 dB, 6.00 dB and 2.00 dB.
Also assume that the substantially consistent impedance that each
of the cross-coupled segments 624, 626 of the MFB filter 602 is
kept at is to be 400 ohms. The gain of 14.00 dB can be achieved by
setting R1a equal to 490.58 ohms and setting R1b equal to 2166.32
ohms. The gain of 10.00 dB can be achieved by setting R1a equal to
572.27 ohms and setting R1b equal to 1328.28 ohms. The gain of 6.00
dB can be achieved by setting R1a equal to 639.44 ohms and setting
R1b equal to 1068.22 ohms. The gain of 2.00 dB can be achieved by
setting R1a equal to 690.59 ohms and setting R1b equal to 950.60
ohms. Negative gains can also be achieved if desired. For example,
a gain of -2.00 dB can be achieved by setting R1a equal to 727.30
ohms and setting R1b equal to 888.85 ohms; and a gain of -4.00 dB
can be achieved by setting R1a equal to 741.15 ohms and setting R1b
equal to 860.00 ohms.
[0108] In the embodiment of FIG. 6, the positive (+) output 619 of
the op-amp 618, the positive output 620 of the fully differential
filter circuitry 612, and the positive output 608 of the MFB filter
602 are at the same node. Similarly, in the embodiment of FIG. 6,
the negative (-) output 621 of the op-amp 618, the negative output
622 of the fully differential filter circuitry 612, and the
negative output 610 of the MFB filter 602 are at the same node.
[0109] The fully differential MFB LPF 602 is one example of a fully
differential adjustable gain device that includes cross-coupled
segments that can be used to adjust the gain of the device while
keeping the input impedance of the device substantially consistent
and keeping the frequency response of the device substantially
consistent. The term "device" as used herein can refer to a chip, a
sub-circuit of a larger circuit included in a chip, a sub-circuit
of a larger circuit included on a printed circuit board (PCB), or
more generally, can be used to refer to a circuit. As will be
described below, further embodiments of the present technology are
directed to other types of fully differential adjustable gain
devices that includes cross-coupled segments (similar to the
cross-coupled segments 624 and 626) that can be used to adjust the
gain of the device while keeping the input impedance of the device
substantially consistent and keeping the frequency response of the
device substantially consistent.
[0110] While it would be preferred to adjust the gain of the fully
differential MFB LPF 602 (and other fully differential adjustable
gain devices described herein) while keeping the input impedance of
the device absolutely consistent and keeping the frequency response
of the device absolutely consistent, in an actual implementation
this would be very difficult if not impossible to achieve. Rather,
what is achievable and acceptable is adjusting the gain of the
fully differential MFB LPF 602 (and other fully differential
adjustable gain devices described herein) while keeping the input
impedance of the device substantially consistent and keeping the
frequency response of the device substantially consistent. The term
"substantially consistent" as used herein refers to within +/-10%
of a specified value for a median gain setting. For example, if the
specified input impedance for a device is 500 ohms, then keeping
that input impedance substantially consistent would be keeping the
input impedance within 500 ohms+/-10%, or more specifically,
keeping the input impedance within the range of 450 ohms to 550
ohms. Similarly, in an actual implementation, keeping a specified
relationship between component values of cross-coupled segments
(e.g., 624 and 626 in FIG. 6) absolutely constant may also not be
achievable. Rather, what is achievable and acceptable is keeping
the specified relationship between component values of
cross-coupled segments (e.g., 624 and 626 in FIG. 6) substantially
constant, wherein the term "substantially constant" refers to
within +/-10% of a specified value. For example, keeping the
relationship represented in Equation(2) shown above substantially
constant means keeping results of Equation(2) within +/-10% of a
specified value. For example, if the result of Equation(2) for a
median gain setting is the value 400, then for other gain settings
that value should be kept within 400+/-10%, or more specifically,
within the range of 360 and 440. In the below discussion of the
embodiments of FIGS. 7-13, the term "constant" may be used for
brevity but can be interpreted as meaning "substantially constant."
Similarly, the term "the same" may be used for brevity but can be
interpreted as meaning "substantially the same."
[0111] Referring to FIG. 7, shown therein is a fully differential
MFB bandpass filter (BPF) 702, according to an embodiment of the
present technology. The MFB BPF 702 can be included in a receiver,
such as the receiver 404 illustrated in FIG. 4, e.g., as the MFB
filter 414 shown in FIG. 4. The fully differential MFB BPF 702,
which can also be referred to herein more succinctly as the MFB
filter 702, is shown as having differential input terminals,
including a negative (-) input terminal 704 and a positive (+)
input terminal 706. The MFB filter 702 is also shown as having
differential output terminals, including a positive (+) output
terminal 708 and a negative (-) output terminal 710. The MFB filter
702 includes a fully differential op-amp 718 including differential
inputs and differential outputs, wherein the differential inputs
include a negative (-) input 713 and a positive (+) input 715, and
the differential outputs include a positive (+) output 719 and a
negative (-) output 721.
[0112] In the MFB filter 702, the positive (+) output 719 of the
op-amp 718 is connected to the negative (-) input 713 of the op-amp
718 by a feedback resistor component 741 having a resistance value
Rf. The negative (-) output 721 of the op-amp 718 is connected to
the positive (+) input 715 of the op-amp 718 by a feedback resistor
component 745 having the same resistance value Rf as the feedback
resistor component 741. The MFB filter 702 also includes feedback
capacitor components 742 and 746 that each have the same
capacitance value Cf. One of the terminals of the feedback
capacitor component 742 is connected to the positive (+) output 719
of the op-amp 718, and the other terminal of the feedback capacitor
component 742 is connected to one of the terminals of the resistor
component 748, which has a resistance value 2*R0. One of the
terminals of the feedback capacitor component 746 is connected to
the negative (-) output 721 of the op-amp 718, and the other
terminal of the feedback capacitor component 746 is connected to
the other one of the terminals of the resistor component 748. One
of the terminals of a capacitor component 743, having a capacitance
value C0, is connected to the negative (-) input 713 of the op-amp
718, and the other one of the terminals of the capacitor component
743 is connected to one of the terminals of the resistor component
748. One of the terminals of a capacitor component 747, having the
capacitance value C0, is connected to the positive (+) input 715 of
the op-amp 718, and the other one of the terminals of the capacitor
component 747 is connected to the other one of the terminals of the
resistor component 748.
[0113] Still referring to FIG. 7, the circuitry within the dashed
lined block labeled 712 can be referred to collectively as fully
differential filter circuitry 712 having differential inputs and
differential outputs, wherein the differential inputs include a
negative (-) input 714 and a positive (+) input 716, and the
differential outputs include a positive (+) output 720 and a
negative (-) output 722. The fully differential filter circuitry
712 can be referred to more generically as fully differential
signal processing circuitry. In FIG. 7, the cross-coupled segment
724 is coupled between the differential input terminals 704, 706 of
the MFB filter 702 and the negative (-) input 714 of the fully
differential filter circuitry 712, wherein the cross-coupled
segment 724 includes a resistor component 723 having a resistance
value R1a, and also includes a resistor component 725 having a
resistance value R1b. Additionally, the cross-coupled segment 726
is coupled between the differential input terminals 704, 706 of the
MFB filter 702 and the positive (+) input 716 of the fully
differential filter circuitry 712, wherein the cross-coupled
segment 726 includes a resistor component 729 having the resistance
value R1a (which is the same resistance as the resistor component
723), and also includes a resistor component 727 having the
resistance R1b value (which is the same resistance as the resistor
component 725). The resistor components 723, 725, 727 and 729 are
adjustable resistor components, and thus, each can be said to have
an adjustable resistance. Accordingly, the resistor components 723
and 729 can be said to have an adjustable resistance value R1a, and
the resistor components 725 and 727 can be said to have an
adjustable resistance value R1b.
[0114] More specifically, as can be appreciated from FIG. 7, the
cross-coupled segment 724 includes the resistor component 723
having the adjustable resistance value R1a and the resistor
component 725 having the adjustable resistance value R1b. The
resistor component 723 is coupled between the negative (-) input
terminal 704 of the MFB filter 702 and the negative (-) input 714
of the fully differential filter circuitry 712. The resistor
component 725 is coupled between the positive (+) input terminal
706 of the MFB filter 702 and the negative (-) input 714 of the
fully differential filter circuitry 712. As can also be appreciated
from FIG. 7, the cross-coupled segment 726 includes the resistor
component 729 having the adjustable resistance value R1a and the
resistor component 727 having the adjustable resistance value R1b.
The resistor component 729 is coupled between the positive (+)
input terminal 706 of the MFB filter 702 and the positive (+) input
716 of the fully differential filter circuitry 712. The resistor
component 727 is coupled between the negative (-) input terminal
704 of the MFB filter 702 and the positive (+) input 716 of the
fully differential filter circuitry 712.
[0115] Vo(s)/Vi(s) for the fully differential MFB BPF 702 is shown
in the following Equation(3):
Vo ( s ) Vi ( s ) = - Gain * s * 1 Cf * Rf s 2 + s * 1 Rf * ( 1 C 0
+ 1 Cf ) + 1 + R 0 / R 1 C 0 * Cf * R 0 * Rf ##EQU00009##
[0116] where, [0117] Vi(s) is the voltage of the differential input
signal, [0118] Vo(s) is the voltage of the differential output
signal, [0119] Gain is equal to (Rf/R1b)-(Rf/R1a), [0120] R0 is
half the resistance of the resistor component 748, [0121] R1 is
equal to (R1a*R1b)/(R1a+R1b), [0122] R1a is the resistance of each
of the resistor components 723 and 729, [0123] R1b is the
resistance of each of the resistor components 725 and 727, [0124]
Rf is the resistance of each of the feedback resistor components
741 and 745, [0125] Cf is the capacitance of each of the feedback
capacitor components 742 and 746, and [0126] s is a variable that
represents complex frequency.
[0127] Beneficially, the gain of the fully differential MFB BPF 702
can be adjusted, without substantially affecting a frequency
response and without substantially affecting an input impedance of
the fully differential MFB BPF 702 (i.e., while keeping the
frequency response substantially consistent and the input impedance
substantially consistent of the fully differential MFB BPF 702), by
only adjusting the resistance R1a (which is the resistance of each
of the resistor component 723 of the cross-coupled segment 724 and
the resistor component 729 of the cross-coupled segment 726), and
adjusting the resistance R1b (which is the resistance of each of
the resistor component 725 of the cross-coupled segment 724 and the
resistor component 727 of the cross-coupled segment 726).
Accordingly, the other passive components of the MFB filter 702
need not be adjusted and can have fixed component values. The
described embodiment enables the MFB filter 702 to be implemented
in a relatively small die area, with relatively easy gain control.
The condition that needs to be met, to keep the frequency response
substantially consistent and the input impedance substantially
consistent of the fully differential MFB BPF 702, is keeping
substantially constant a specified relationship between component
values of the cross-coupled segments 724 and 726. More
specifically, the gain of the MFB filter 702 can be adjusted, while
keeping the frequency response of the MFB filter 702 substantially
consistent and keeping the input impedance of the MFB filter 702
substantially consistent, by adjusting a value of the adjustable
resistance R1a and a value of adjustable resistance R1b, which are
resistance values of resistor components included in each of the
cross-coupled segments 724 and 726, while keeping substantially
constant the following Equation(2):
R 1 a * R 1 b R 1 a + R 1 b . ##EQU00010##
[0128] Referring now to FIG. 8, shown therein is a fully
differential MFB high pass filter (HPF) 802, according to an
embodiment of the present technology. The MFB HPF 802 can be
included in a receiver, such as the receiver 404 illustrated in
FIG. 4, e.g., as the MFB filter 414 shown in FIG. 4. The fully
differential MFB HPF 802, which can also be referred to herein more
succinctly as the MFB filter 802, is shown as having differential
input terminals, including a negative (-) input terminal 804 and a
positive (+) input terminal 806. The MFB filter 802 is also shown
as having differential output terminals, including a positive (+)
output terminal 808 and a negative (-) output terminal 810. The MFB
filter 802 includes a fully differential op-amp 818 including
differential inputs and differential outputs, wherein the
differential inputs include a negative (-) input 813 and a positive
(+) input 815, and the differential outputs include a positive (+)
output 819 and a negative (-) output 821. The MFB HPF filter 802 is
a fully differential filter because it includes both differential
inputs and differential outputs.
[0129] In the MFB filter 802, the positive (+) output 819 of the
op-amp 818 is connected to the negative (-) input 813 of the op-amp
818 by a feedback resistor component 841 having a resistance value
Rf. The negative (-) output 821 of the op-amp 818 is connected to
the positive (+) input 815 of the op-amp 818 by a feedback resistor
component 845 having the same resistance value Rf as the feedback
resistor component 841. The MFB filter 802 also includes feedback
capacitor components 842 and 846 that each have the same
capacitance value Cf. One of the terminals of the feedback
capacitor component 842 is connected to the positive (+) output 819
of the op-amp 818, and the other terminal of the feedback capacitor
component 842 is connected to one of the terminals of the resistor
component 848, which has a resistance value 2*R0. One of the
terminals of the feedback capacitor component 846 is connected to
the negative (-) output 821 of the op-amp 818, and the other
terminal of the feedback capacitor component 846 is connected to
the other one of the terminals of the resistor component 848. One
of the terminals of a capacitor component 843, having a capacitance
value C0, is connected to the negative (-) input 813 of the op-amp
818, and the other one of the terminals of the capacitor component
843 is connected to one of the terminals of the resistor component
848. One of the terminals of a capacitor component 847, having the
capacitance value C0, is connected to the positive (+) input 815 of
the op-amp 818, and the other one of the terminals of the capacitor
component 847 is connected to the other one of the terminals of the
resistor component 848.
[0130] Still referring to FIG. 8, the circuitry within the dashed
lined block labeled 812 can be referred to collectively as fully
differential filter circuitry 812 having differential inputs and
differential outputs, wherein the differential inputs include a
negative (-) input 814 and a positive (+) input 816, and the
differential outputs include a positive (+) output 820 and a
negative (-) output 822. The fully differential filter circuitry
812 can be referred to more generically as fully differential
signal processing circuitry. In FIG. 8, the cross-coupled segment
824 is coupled between the differential input terminals 804, 806 of
the MFB filter 802 and the negative (-) input 814 of the fully
differential filter circuitry 812, wherein the cross-coupled
segment 824 includes a capacitor component 823 having a capacitance
value C1a, and also includes a capacitor component 825 having a
capacitance value C1b. The cross-coupled segment 826 is coupled
between the differential input terminals 804, 806 of the MFB filter
802 and the positive (+) input 816 of the fully differential filter
circuitry 812, wherein the cross-coupled segment 826 includes a
capacitor component 829 having the capacitance value C1a (which is
the same capacitance as the capacitor component 823), and also
includes a capacitor component 827 having the capacitance C1b value
(which is the same capacitance as the capacitor component 825). The
capacitor components 823, 825, 827 and 829 are adjustable capacitor
components, and thus, each can be said to have an adjustable
capacitance. Accordingly, the capacitor components 823 and 829 can
be said to have an adjustable capacitance value C1a, and the
capacitor components 825 and 827 can be said to have an adjustable
capacitance value C1b.
[0131] More specifically, as can be appreciated from FIG. 8, the
cross-coupled segment 824 includes the capacitor component 823
having the adjustable capacitance value C1a and the capacitor
component 825 having the adjustable capacitance value C1b. The
capacitor component 823 is coupled between the negative (-) input
terminal 804 of the MFB filter 802 and the negative (-) input 814
of the fully differential filter circuitry 812. The capacitor
component 825 is coupled between the positive (+) input terminal
806 of the MFB filter 802 and the negative (-) input 814 of the
fully differential filter circuitry 812. As can also be appreciated
from FIG. 8, the cross-coupled segment 826 includes the capacitor
component 829 having the adjustable capacitance value C1a and the
capacitor component 827 having the adjustable capacitance value
C1b. The capacitor component 829 is coupled between the positive
(+) input terminal 806 of the MFB filter 802 and the positive (+)
input 816 of the fully differential filter circuitry 812. The
capacitor component 827 is coupled between the negative (-) input
terminal 804 of the MFB filter 802 and the positive (+) input 816
of the fully differential filter circuitry 812.
[0132] Vo(s)/Vi(s) for the fully differential MFB HPF 802 is shown
in the following Equation(4):
Vo ( s ) Vi ( s ) = Gain * s 2 * C 0 * Cf * Rf s 2 * C 0 * Cf * Rf
+ s ( C 0 + C 1 + Cf ) + 1 R 0 ##EQU00011##
[0133] where, [0134] Vi(s) is the voltage of the differential input
signal, [0135] Vo(s) is the voltage of the differential output
signal, [0136] Gain is equal to (C1a-C1b)/Cf, [0137] R0 is half the
resistance of the resistor component 848, [0138] C1 is equal to
C1a+C1b, [0139] C1a is the capacitance of each of the capacitor
components 823 and 829, [0140] C1b is the capacitance of each of
the capacitor components 825 and 827, [0141] Rf is the resistance
of each of the feedback resistor components 841 and 845, [0142] Cf
is the capacitance of each of the feedback capacitor components 842
and 846, and [0143] s is a variable that represents complex
frequency.
[0144] Beneficially, the gain of the fully differential MFB HPF 802
can be adjusted, without substantially affecting a frequency
response and without substantially affecting an input impedance of
the fully differential MFB HPF 802 (i.e., while keeping the
frequency response substantially consistent and the input impedance
substantially consistent of the fully differential MFB HPF 802), by
only adjusting capacitance C1a (which is the capacitance of each of
the capacitor component 823 of the cross-coupled segment 824 and
the capacitor component 829 of the cross-coupled segment 826), and
adjusting the capacitance C1b (which is the capacitance of each of
the capacitor component 825 of the cross-coupled segment 824 and
the capacitor component 827 of the cross-coupled segment 826).
Accordingly, the other passive components of the MFB filter 802
need not be adjusted and can have fixed component values. The
described embodiment enables the MFB filter 802 to be implemented
in a relatively small die area, with relatively easy gain control.
The condition that needs to be met, to keep the frequency response
substantially consistent and the input impedance substantially
consistent of the fully differential MFB HPF 802, is keeping
substantially constant a specified relationship between component
values of the cross-coupled segments 824 and 826. More
specifically, the gain of the MFB filter 802 can be adjusted, while
keeping the frequency response of the MFB filter 802 substantially
consistent and keeping the input impedance of the MFB filter 802
substantially consistent, by adjusting a value of the adjustable
capacitance C1a and a value of adjustable capacitance C1b, which
are capacitance values of capacitor components included in each of
the cross-coupled segments 824 and 826, while keeping substantially
constant the following Equation(5): C1a+C1b.
[0145] In the embodiment of FIG. 8, the positive (+) output 819 of
the op-amp 818, the positive output 820 of the fully differential
filter circuitry 812, and the positive output 808 of the MFB filter
802 are at the same node. Similarly, in the embodiment of FIG. 8,
the negative (-) output 821 of the op-amp 818, the negative output
822 of the fully differential filter circuitry 812, and the
negative output 810 of the MFB filter 802 are at the same node.
[0146] Referring now to FIG. 9, shown therein is a fully
differential variable gain amplifier (VGA) 902, according to an
embodiment of the present technology. The VGA 902 can be included
in a receiver, such as the receiver 404 illustrated in FIG. 4,
e.g., as the VGA 416 shown in FIG. 4. The fully differential VGA
902, which can also be referred to herein more succinctly as the
VGA 902, is shown as having differential input terminals, including
a negative (-) input terminal 904 and a positive (+) input terminal
906. The VGA 902 is also shown as having differential output
terminals, including a positive (+) output terminal 908 and a
negative (-) output terminal 910. The VGA 902 includes a fully
differential op-amp 918 including differential inputs and
differential outputs, wherein the differential inputs include a
negative (-) input 913 and a positive (+) input 915, and the
differential outputs include a positive (+) output 919 and a
negative (-) output 921. The FGA 902 is a fully differential
amplifier because it includes both differential inputs and
differential outputs.
[0147] In the VGA 902, the positive (+) output 919 of the op-amp
918 is connected to the negative (-) input 913 of the op-amp 918 by
a feedback capacitor component 942 having a capacitance value Cf.
The negative (-) output 921 of the op-amp 918 is connected to the
positive (+) input 915 of the op-amp 918 by a feedback capacitor
component 946 having the same capacitance value Cf as the feedback
capacitor component 942. The VGA 902 also includes feedback
resistor components 941 and 945 that each have the same resistance
value Rf. The feedback resistor component 941 is connected in
parallel with the feedback capacitor component 942, and thus, the
positive (+) output 919 of the op-amp 918 is also connected to the
negative (-) input 913 of the op-amp 918 by the feedback resistor
component 941 having a resistance value Rf. The feedback resistor
component 945 is connected in parallel with the feedback capacitor
component 946, and thus, the negative (-) output 921 of the op-amp
918 is also connected to the positive (+) input 915 of the op-amp
918 by the feedback resistor component 945 having the same
resistance value Rf as the feedback resistor component 941.
[0148] Still referring to FIG. 9, the circuitry within the dashed
lined block labeled 912 can be referred to collectively as fully
differential gain circuitry 912 having differential inputs and
differential outputs, wherein the differential inputs include a
negative (-) input 914 and a positive (+) input 916, and the
differential outputs include a positive (+) output 920 and a
negative (-) output 922. The fully differential filter circuitry
912 can be referred to more generically as fully differential
signal processing circuitry. In FIG. 9, the cross-coupled segment
924 is coupled between the differential input terminals 904, 906 of
the VGA 902 and the negative (-) input 914 of the fully
differential filter circuitry 912, wherein the cross-coupled
segment 924 includes a resistor component 923 having a resistance
value R1a, and also includes a resistor component 925 having a
resistance value R1b. Additionally, the cross-coupled segment 926
is coupled between the differential input terminals 904, 906 of the
VGA 902 and the positive (+) input 916 of the fully differential
filter circuitry 912, wherein the cross-coupled segment 926
includes a resistor component 929 having the resistance value R1a
(which is the same resistance as the resistor component 923), and
also includes a resistor component 927 having the resistance R1b
value (which is the same resistance as the resistor component 925).
The resistor components 923, 925, 927 and 929 are adjustable
resistor components, and thus, each can be said to have an
adjustable resistance. Accordingly, the resistor components 923 and
929 can be said to have an adjustable resistance value R1a, and the
resistor components 925 and 927 can be said to have an adjustable
resistance value R1b.
[0149] More specifically, as can be appreciated from FIG. 9, the
cross-coupled segment 924 includes the resistor component 923
having the adjustable resistance value R1a and the resistor
component 925 having the adjustable resistance value R1b. The
resistor component 923 is coupled between the negative (-) input
terminal 904 of the VGA 902 and the negative (-) input 914 of the
fully differential filter circuitry 912. The resistor component 925
is coupled between the positive (+) input terminal 906 of the VGA
902 and the negative (-) input 914 of the fully differential filter
circuitry 912. As can also be appreciated from FIG. 9, the
cross-coupled segment 926 includes the resistor component 929
having the adjustable resistance value R1a and the resistor
component 927 having the adjustable resistance value R1b. The
resistor component 929 is coupled between the positive (+) input
terminal 906 of the VGA 902 and the positive (+) input 916 of the
fully differential filter circuitry 912. The resistor component 927
is coupled between the negative (-) input terminal 904 of the VGA
902 and the positive (+) input 916 of the fully differential filter
circuitry 912.
[0150] Vo(s)/Vi(s) for the fully differential VGA 902 is shown in
the following Equation(6):
Vo ( s ) Vi ( s ) = - Gain * 1 1 + ( s * Rf * Cf ) ##EQU00012##
[0151] where, [0152] Vi(s) is the voltage of the differential input
signal, [0153] Vo(s) is the voltage of the differential output
signal, [0154] Gain is equal to Rf*(R1a-R1b)/(R1a*R1b), [0155] R1a
is the resistance of each of the resistor components 923 and 929,
[0156] R1b is the resistance of each of the resistor components 925
and 927, [0157] Rf is the resistance of each of the feedback
resistor components 941 and 945, [0158] Cf is the capacitance of
each of the feedback capacitor components 942 and 946, and [0159] s
is a variable that represents complex frequency.
[0160] Beneficially, the gain of the VGA 902 can be adjusted,
without substantially affecting a frequency response and without
substantially affecting an input impedance of the fully
differential VGA 902 (i.e., while keeping the frequency response of
the fully differential VGA 902 substantially consistent, and
keeping the input impedance of the fully differential VGA 902
substantially consistent), by only adjusting resistance R1a (which
is the resistance of each of the resistor component 923 of the
cross-coupled segment 924 and the resistor component 929 of the
cross-coupled segment 926), and adjusting the resistance R1b (which
is the resistance of each of the resistor component 925 of the
cross-coupled segment 924 and the resistor component 927 of the
cross-coupled segment 926). Accordingly, the other passive
components of the VGA 902 need not be adjusted and can have fixed
component values. The described embodiment enables the VGA 902 to
be implemented in a relatively small die area, with relatively easy
gain control. The condition that needs to be met, to keep the
frequency response substantially consistent and the input impedance
substantially consistent of the fully differential VGA 902, is
keeping substantially constant a specified relationship between
component values of the cross-coupled segments 924 and 926. More
specifically, the gain of the VGA 902 can be adjusted, while
keeping the frequency response of the VGA 902 substantially
consistent and the input impedance of the VGA substantially
consistent, by adjusting a value of the adjustable resistance R1a
and a value of adjustable resistance R1b, which are resistance
values of resistor components included in each of the cross-coupled
segments 924 and 926, while keeping substantially constant the
following Equation(2):
R 1 a * R 1 b R 1 a + R 1 b . ##EQU00013##
[0161] In the embodiment of FIG. 9, the positive (+) output 919 of
the op-amp 918, the positive output 920 of the fully differential
filter circuitry 912, and the positive output 908 of the VGA 902
are at the same node. Similarly, in the embodiment of FIG. 9, the
negative (-) output 921 of the op-amp 918, the negative output 922
of the fully differential filter circuitry 912, and the negative
output 910 of the VGA 902 are at the same node.
[0162] As was mentioned above in the discussions of FIGS. 6, 7, 8
and 9, the circuitry within the dashed lined blocks labeled 612,
712, 812, and 912 (in FIGS. 6, 7, 8 and 9, respectively) can be
referred to generically as fully differential signal processing
circuitry. Referring now to FIG. 10, illustrated therein is a fully
differential adjustable gain device 1002 that includes differential
input terminals including a negative (-) input terminal 1004 and a
positive (+) input terminal 1006, and differential output terminals
including a positive (+) output terminal 1008 and a negative (-)
output terminal 1010. The fully differential adjustable gain device
1002 is shown as including fully differential signal processing
circuitry 1012 including differential inputs and differential
outputs, the differential inputs including a negative (-) input
1014 and a positive (+) input 1016, the differential outputs
including a positive (+) output 1020 and a negative (-) output
1022. The positive (+) output 1020 of the fully differential signal
processing circuitry 1012 provides the positive (+) output terminal
1008 of the fully differential adjustable gain device 1002. The
negative (-) output 1022 of the fully differential signal
processing circuitry 1012 provides the negative (-) output terminal
1010 of the fully differential adjustable gain device 1002. A first
cross-coupled segment 1024 is coupled between the differential
input terminals 1004, 1006 of the fully differential adjustable
gain device 1002 and the negative (-) input 1014 of the fully
differential signal processing circuitry 1012. A second
cross-coupled segment 1026 is coupled between the differential
input terminals 1004, 1006 of the fully differential adjustable
gain device 1002 and the positive (+) input 1016 of the fully
differential signal processing circuitry 1012. As can be
appreciated from the above discussion of FIGS. 6, 7, 8, and 9, the
fully differential signal processing circuitry 1012 can be block
612 in FIG. 6, block 712 in FIG. 7, or block 912 in FIG. 9, but is
not limited thereto. As can be appreciated from the above
discussion of FIGS. 6, 7, 8, and 9, the cross-coupled segment 1024
can be the cross-coupled segment 624 in FIG. 6, 724 in FIG. 7, or
924 in FIG. 9; and the cross-coupled segment 1026 can be the
cross-coupled segment 626 in FIG. 6, 726 in FIG. 7, or 926 in FIG.
9. As can be appreciated from the above discussion of FIGS. 6, 7,
and 9, the fully differential adjustable gain device 1002 has a
gain that is adjustable by adjusting one or more component values
of the cross-coupled segments 1024 and 1026, while maintaining a
substantially consistent frequency response and a substantially
consistent input impedance of the fully differential adjustable
gain device, so long as a specified relationship between the
component values of the cross-coupled segments 1024 and 1026 is
kept substantially constant. In FIG. 10, the cross-coupled segments
1024 and 1026 are shown as including resistor components (1023,
1025, 1027 and 1029), as was also the case in the embodiments
described above with reference to FIGS. 6, 7, and 9. However, as
was described above with reference to FIG. 8, cross-coupled
segments can alternatively include capacitor components. It is also
possible that cross-coupled segments include inductor components,
as will be described below with reference to FIG. 13. The
adjustable gain device 1002 is a fully differential device because
it includes both differential inputs and differential outputs.
[0163] More generally, in accordance with certain embodiments of
the present technology, a first cross-coupled segment (e.g., 624,
724, 824, 924, or 1024) includes a first passive component having a
first adjustable component value (e.g., R1a or C1a) and a second
passive component having a second adjustable component value (e.g.,
R1b or C1b), wherein the first passive component is coupled between
the negative (-) input terminal of the fully differential
adjustable gain device and the negative (-) input of the fully
differential signal processing circuitry, and the second passive
component is coupled between the positive (+) input terminal of the
fully differential adjustable gain device and the negative (-)
input of the fully differential signal processing circuitry.
Similarly, a second cross-coupled segment (e.g., 626, 726, 826,
926, or 1026) includes a third passive component having the first
adjustable component value (e.g., R1a or C1a) and a fourth passive
component having the second adjustable component value (e.g., R1b
or C1b), wherein the third passive component is coupled between the
positive (+) input terminal of the fully differential adjustable
gain device and the positive (+) input of the fully differential
signal processing circuitry, and the fourth passive component is
coupled between the negative (-) input terminal of the fully
differential adjustable gain device and the positive (+) input of
the fully differential signal processing circuitry.
[0164] Passive components, such as resistors, capacitor, and
inductors, can also be referred to as impedance components that
have impedance values. Where the passive components have adjustable
values, they can be referred to as adjustable impedance components
that have adjustable impedance values. FIG. 11 illustrates more
generally how a fully differential adjustable gain device 1102 can
include differential input terminals including a negative (-) input
terminal 1104 and a positive (+) input terminal 1106, and
differential output terminals including a positive (+) output
terminal 1108 and a negative (-) output terminal 1110. The fully
differential adjustable gain device 1102 is shown as including
fully differential signal processing circuitry 1112 including
differential inputs and differential outputs, the differential
inputs including a negative (-) input 1114 and a positive (+) input
1116, the differential outputs including a positive (+) output 1120
and a negative (-) output 1122. The positive (+) output 1120 of the
fully differential signal processing circuitry 1112 provides the
positive (+) output terminal 1108 of the fully differential
adjustable gain device 1102. The negative (-) output 1122 of the
fully differential signal processing circuitry 1112 provides the
negative (-) output terminal 1110 of the fully differential
adjustable gain device 1102. A first cross-coupled segment 1124 is
coupled between the differential input terminals 1104, 1106 of the
fully differential adjustable gain device 1102 and the negative (-)
input 1114 of the fully differential signal processing circuitry
1124. A second cross-coupled segment 1126 is coupled between the
differential input terminals 1104, 1106 of the fully differential
adjustable gain device 1102 and the positive (+) input 1116 of the
fully differential signal processing circuitry 1112. The adjustable
gain device 1102 is a fully differential device because it includes
both differential inputs and differential outputs.
[0165] As can be appreciated from the above discussion of FIGS. 6,
7, 8, and 9, the fully differential signal processing circuitry
1112 can be block 612 in FIG. 6, block 712 in FIG. 7, block 812 in
FIG. 8, or block 912 in FIG. 9, but is not limited thereto. As can
be appreciated from the above discussion of FIGS. 6, 7, 8, and 9,
the cross-coupled segment 1124 can be the cross-coupled segment 624
in FIG. 6, 724 in FIG. 7, 824 in FIG. 8, or 924 in FIG. 9; and the
cross-coupled segment 1126 can be the cross-coupled segment 626 in
FIG. 6, 726 in FIG. 7, 826 in FIG. 8, or 926 in FIG. 9. As can be
appreciated from the above discussion of FIGS. 6, 7, 8, and 9, the
fully differential adjustable gain device 1102 has a gain that is
adjustable by adjusting one or more impedance values of the
cross-coupled segments 1124 and 1126, while maintaining a
substantially consistent frequency response and a substantially
consistent input impedance of the fully differential adjustable
gain device 1102, so long as a specified relationship between the
impedance values of the cross-coupled segments 1124 and 1126 is
kept substantially constant for any given value of the complex
frequency variable s.
[0166] In FIG. 11, the cross-coupled segment 1124 is shown as
including impedance component 1123 having an adjustable impedance
value Z1a, and an impedance component 1125 having an adjustable
impedance value Z1b; and the cross-coupled segment 1126 is shown as
including impedance component 1129 having the adjustable impedance
value Z1a, and an impedance component 1127 having the adjustable
impedance value Z1b. The gain of the fully differential adjustable
gain device 1102 is adjustable by adjusting the first adjustable
impedance value (Z1a) of each of the impedance component 1123 of
the cross-coupled segment 1124 and the impedance component 1129 of
the cross-coupled segment 1126, and adjusting the second adjustable
impedance value (Z1b) of each of the impedance component 1125 of
the cross-coupled segment 1124 and the impedance component 1127 of
the cross-coupled segment 1126. The specified relationship between
the component values of the cross-coupled segments 1124 and 1126
that is kept constant for any given value of s is the following
Equation(7):
Z 1 a ( s ) * Z 1 b ( s ) Z 1 a ( s ) + Z 1 b ( s ) .
##EQU00014##
[0167] FIG. 11 also shows a controller 1130, which can be part of
the fully differential adjustable gain device 1102 or can be
external thereto and in communication with the fully differential
adjustable gain device 1102. The controller 1130 can be used to
adjust the values of the adjustable impedance values (Z1a and Z1b)
of the impedance components 1123, 1125, 1127, and 1129 included in
the cross-coupled segments 1124 and 1126 to achieve different gain
settings while keeping the frequency response of the fully
differential adjustable gain device 1102 substantially consistent,
and keeping the input impedance of the fully differential
adjustable gain device 1102 substantially consistent. The
controller 1130 can be implemented using a processor, a state
machine, or an application specific integrated circuit (ASIC), but
is not limited thereto. For an example, where each of the impedance
components 1123, 1125, 1127, and 1129 is implemented using a bank
of resistor, capacitor, and/or inductor components, the controller
1130 can control switches (not shown) to switch various passive
components of the bank into or out of the circuit to achieve a
desired impedance value. The other embodiments described herein,
including those described with reference to FIGS. 6-10 and 12-13
can also be under the control of a similar controller 1130 that is
part of the device shown in the FIG., or is external to the device.
In other words, while controllers are not shown in the other FIGS.,
each such other FIG. can also have been shown to include a similar
controller.
[0168] FIG. 12 is similar to FIGS. 10 and 11 in that it shows a
fully differential adjustable gain device 1202 can include
differential input terminals including a negative (-) input
terminal 1204 and a positive (+) input terminal 1206, and
differential output terminals including a positive (+) output
terminal 1208 and a negative (-) output terminal 1210. The fully
differential adjustable gain device 1202 is shown as including
fully differential signal processing circuitry 1212 including
differential inputs and differential outputs, the differential
inputs including a negative (-) input 1214 and a positive (+) input
1216, the differential outputs including a positive (+) output 1230
and a negative (-) output 1222. The positive (+) output 1220 of the
fully differential signal processing circuitry 1212 provides the
positive (+) output terminal 1208 of the fully differential
adjustable gain device 1202. The negative (-) output 1222 of the
fully differential signal processing circuitry 1212 provides the
negative (-) output terminal 1210 of the fully differential
adjustable gain device 1202. A first cross-coupled segment 1224 is
coupled between the differential input terminals 1204, 1206 of the
fully differential adjustable gain device 1202 and the negative (-)
input 1214 of the fully differential signal processing circuitry
1224. A second cross-coupled segment 1226 is coupled between the
differential input terminals 1204, 1206 of the fully differential
adjustable gain device 1202 and the positive (+) input 1216 of the
fully differential signal processing circuitry 1212. The adjustable
gain device 1202 is a fully differential device because it includes
both differential inputs and differential outputs.
[0169] In FIG. 12, the cross-coupled segment 1224 is shown as
including capacitor component 1223 (which is a type of impedance
component) having an adjustable capacitance value C1a, and a
capacitor component 1225 having an adjustable capacitance value
C1b; and the cross-coupled segment 1226 is shown as including a
capacitor component 1229 having the adjustable capacitance value
C1a, and a capacitor component 1227 having the adjustable
capacitance value C1b. Such capacitor components are specific types
of impedance components, and such capacitance values are specific
types of impedance values. The gain of the fully differential
adjustable gain device 1202 is adjustable by adjusting the
adjustable capacitor value (C1a) of each of the capacitor component
1223 of the cross-coupled segment 1224 and the capacitor component
1229 of the cross-coupled segment 1226, and the adjustable
capacitor value (C1b) of each of the capacitor component 1225 of
the cross-coupled segment 1224 and the capacitor component 1227 of
the cross-coupled segment 1226. The impedance of each of the
capacitor components 1223 and 1229 is equal to 1/(s*C1a); and the
impedance of each of the capacitor components 1225 and 1227 is
equal to 1/(s*C1b). The specified relationship between the
component values of the cross-coupled segments 1224 and 1226 that
is kept substantially constant (i.e., in order to keep the
frequency response of the fully differential adjustable gain device
1202 substantially consistent, and keep the input impedance of the
fully differential adjustable gain device 1202 substantially
consistent) is the following Equation(5): C1a+C1b.
[0170] FIG. 13 is similar to FIGS. 10, 11 and 12 in that it is
shows a fully differential adjustable gain device 1302 can include
differential input terminals including a negative (-) input
terminal 1304 and a positive (+) input terminal 1306, and
differential output terminals including a positive (+) output
terminal 1308 and a negative (-) output terminal 1310. The fully
differential adjustable gain device 1302 is shown as including
fully differential signal processing circuitry 1312 including
differential inputs and differential outputs, the differential
inputs including a negative (-) input 1314 and a positive (+) input
1316, the differential outputs including a positive (+) output 1320
and a negative (-) output 1322. The positive (+) output 1320 of the
fully differential signal processing circuitry 1312 provides the
positive (+) output terminal 1308 of the fully differential
adjustable gain device 1302. The negative (-) output 1322 of the
fully differential signal processing circuitry 1312 provides the
negative (-) output terminal 1310 of the fully differential
adjustable gain device 1302. A first cross-coupled segment 1324 is
coupled between the differential input terminals 1304, 1306 of the
fully differential adjustable gain device 1302 and the negative (-)
input 1314 of the fully differential signal processing circuitry
1312. A second cross-coupled segment 1326 is coupled between the
differential input terminals 1304, 1306 of the fully differential
adjustable gain device 1302 and the positive (+) input 1316 of the
fully differential signal processing circuitry 1312. The adjustable
gain device 1302 is a fully differential device because it includes
both differential inputs and differential outputs.
[0171] In FIG. 13, the cross-coupled segment 1324 is shown as
including an inductor component 1323 (which is a type of impedance
component) having an adjustable inductance value L1a, and an
inductor component 1325 having an adjustable inductance value L1b;
and the cross-coupled segment 1326 is shown as including a inductor
component 1329 having the adjustable inductance value L1a, and an
inductor component 1327 having the adjustable inductance value L1b.
Such inductor components are specific types of impedance
components, and such inductance values are specific types of
impedance values. The gain of the fully differential adjustable
gain device 1302 is adjustable by adjusting the adjustable inductor
value L1a of each of the inductor component 1323 of the
cross-coupled segment 1324 and the inductor component 1329 of the
cross-coupled segment 1326, and adjusting the adjustable inductor
value L1b of each of the inductor component 1325 of the
cross-coupled segment 1324 and the inductor component 1327 of the
cross-coupled segment 1326. The impedance of each of the inductor
components 1323 and 1329 is equal to s*L1a; and the impedance of
each of the inductor components 1324 and 1327 is equal to s*L1b.
The specified relationship between the component values of the
cross-coupled segments 1324 and 1326 that is kept substantially
constant (i.e., in order to keep the frequency response of the
fully differential adjustable gain device 1302 substantially
consistent, and keep the input impedance of the fully differential
adjustable gain device 1302 substantially consistent) is the
following Equation(8):
( L 1 a * L 1 b ) L 1 a + L 1 b . ##EQU00015##
[0172] While it would be preferred to adjust the gain of the
various fully differential adjustable gain devices described herein
while keeping the input impedance of the device absolutely constant
and keeping the frequency response of the device absolutely
consistent, in an actual implementation this would be very
difficult if not impossible to achieve. Rather, what is achievable
is acceptable is adjusting the gain of such a fully differential
adjustable gain device while keeping the input impedance of the
device substantially consistent and keeping the frequency response
of the device substantially consistent. As noted above, the term
"substantially constant" as used herein refers to within +/-10% of
a specified value, and the term "substantially consistent" as used
herein refers to within +/-10% of a response for a median gain
setting. For example, if the specified input impedance for a device
is 500 ohms, then keeping that input impedance substantially
consistent would be keeping the input impedance within 500
ohms+/-10%, or more specifically, keeping the input impedance
within the range of 450 ohms to 550 ohms. Similarly, in an actual
implementation, keeping a specified relationship between component
values of cross-coupled segments (e.g., 1124 and 1126 in FIG. 11)
absolutely constant may also not be achievable. Rather, what is
achievable and acceptable is keeping the specified relationship
between component values of cross-coupled segments (e.g., 1124 and
1126 in FIG. 11) substantially constant, wherein the term
"substantially constant" refers to within +/-10% of a specified
value. For example, keeping the relationship represented in
Equation(2) shown above substantially constant means keeping
results of Equation(2) within +/-10% of a specified value. For
example, if the result of Equation(2) for a median gain setting is
the value 400, then for other gain settings that value should be
kept within 400+/-10%, or more specifically, within the range of
360 and 440. In the above discussion of the embodiments of FIGS.
6-13, the term "constant" may be used for brevity but can be
interpreted as meaning "substantially constant." Similarly, the
term "the same" may be used for brevity but can be interpreted as
meaning "substantially the same." Accordingly, where two impedance
components are said to have "the same" impedance value, this can be
interpreted as the two impedance components having substantially
the same impedance value, and more specifically, be interpreted as
the two impedance values being within +/-10% of a mean (i.e.,
average) of the impedance values for the two impedance components.
For example, impedance values of 200 ohms and 210 ohms can be
considered to be substantially the same, since both values are
within +/-10% of the average of the two impedance values, i.e.,
within +/-10% of 205 ohms.
[0173] In the various embodiments described above with reference to
FIGS. 6-13, impedance components that were described as having an
adjustable impedance were shown and described as being either
resistor components, capacitor components, or inductor components.
It would also be possible that such impedance components are
combinations of resistor, capacitor and/or inductor components. In
other words, impedance components having an adjustable impedance
can alternative be, e.g., RC components, RL components, RCL
components, or CL components, but are not limited thereto.
[0174] FIG. 14 is a high-level flow diagram that is used to
summarize methods according to various embodiments of the present
technology. Such methods are for use with a fully differential
adjustable gain device (e.g., 602, 702, 802, 902, 1002, 1102, 1202,
or 1302) that includes differential input terminals, differential
output terminals, and fully differential signal processing
circuitry (e.g., 612, 712, 812, 912, 1012, 1112, 1212, or 1301),
wherein the fully differential signal processing circuitry includes
differential inputs and differential outputs. A positive (+) output
of the fully differential signal processing circuitry provides a
positive (+) output terminal of the fully differential adjustable
gain device. A negative (-) output of the fully differential signal
processing circuitry provides the negative (-) output terminal of
the fully differential adjustable gain device. Additional details
of the fully differential adjustable gain devices with which such
embodiments can be used are described above with reference to FIGS.
6-13.
[0175] Referring to FIG. 14, step 1402 involves coupling a first
cross-coupled segment between the differential input terminals of
the fully differential adjustable gain device and the negative (-)
input of the fully differential signal processing circuitry. Step
1404 involves coupling a second cross-coupled segment between the
differential input terminals of the fully differential adjustable
gain device and the positive (+) input of the fully differential
signal processing circuitry. Exemplary first and second
cross-coupled segments, referred to in steps 1402 and 1404, include
cross-coupled segments 624 and 626 in FIG. 6, cross-coupled
segments 724 and 726 in FIG. 7, cross-coupled segments 824 and 826
in FIG. 8, cross-coupled segments 924 and 926 in FIG. 9,
cross-coupled segments 1024 and 1026 in FIG. 10, cross-coupled
segments 1124 and 1126 in FIG. 11, cross-coupled segments 1224 and
1226 in FIG. 12, and cross-coupled segments 1324 and 1326 in FIG.
13.
[0176] Still referring to FIG. 14, step 1406 involves adjusting a
gain of the fully differential adjustable gain device, while
maintaining a substantially consistent frequency response and a
substantially consistent input impedance of the fully differential
adjustable gain device, by adjusting one or more component values
of the first and second cross-coupled segments while keeping
substantially constant a specified relationship between the
component values of the first and second cross-coupled segments.
The component values that are adjusted at step 1406 can be values
of passive components of the first and second cross-coupled
segments, each of which has a respective adjustable impedance
value. Such impedance values can be, e.g., resistance values,
capacitance values, inductance values, or combinations thereof,
depending upon implementation. Further features of the methods
summarized with reference to FIG. 14 can be appreciated from the
above description of FIGS. 6-13.
[0177] It is understood that the present subject matter may be
embodied in many different forms and should not be construed as
being limited to the embodiments set forth herein. Rather, these
embodiments are provided so that this subject matter will be
thorough and complete and will fully convey the disclosure to those
skilled in the art. Indeed, the subject matter is intended to cover
alternatives, modifications and equivalents of these embodiments,
which are included within the scope and spirit of the subject
matter as defined by the appended claims. Furthermore, in the
following detailed description of the present subject matter,
numerous specific details are set forth in order to provide a
thorough understanding of the present subject matter. However, it
will be clear to those of ordinary skill in the art that the
present subject matter may be practiced without such specific
details.
[0178] Aspects of the present disclosure are described herein with
reference to flowchart illustrations and/or block diagrams of
methods, apparatuses (systems) and computer program products
according to embodiments of the disclosure. It will be understood
that each block of the flowchart illustrations and/or block
diagrams, and combinations of blocks in the flowchart illustrations
and/or block diagrams, can be implemented by computer program
instructions. These computer program instructions may be provided
to a processor of a general purpose computer, special purpose
computer, or other programmable data processing apparatus to
produce a machine, such that the instructions, which execute via
the processor of the computer or other programmable instruction
execution apparatus, create a mechanism for implementing the
functions/acts specified in the flowchart and/or block diagram
block or blocks.
[0179] The description of the present disclosure has been presented
for purposes of illustration and description, but is not intended
to be exhaustive or limited to the disclosure in the form
disclosed. Many modifications and variations will be apparent to
those of ordinary skill in the art without departing from the scope
and spirit of the disclosure. The aspects of the disclosure herein
were chosen and described in order to best explain the principles
of the disclosure and the practical application, and to enable
others of ordinary skill in the art to understand the disclosure
with various modifications as are suited to the particular use
contemplated.
[0180] The disclosure has been described in conjunction with
various embodiments. However, other variations and modifications to
the disclosed embodiments can be understood and effected from a
study of the drawings, the disclosure, and the appended claims, and
such variations and modifications are to be interpreted as being
encompassed by the appended claims. In the claims, the word
"comprising" does not exclude other elements or steps, and the
indefinite article "a" or "an" does not exclude a plurality.
[0181] For purposes of this document, it should be noted that the
dimensions of the various features depicted in the figures may not
necessarily be drawn to scale.
[0182] For purposes of this document, reference in the
specification to "an embodiment," "one embodiment," "some
embodiments," or "another embodiment" may be used to describe
different embodiments or the same embodiment.
[0183] For purposes of this document, a connection may be a direct
connection or an indirect connection (e.g., via one or more other
parts). In some cases, when an element is referred to as being
connected or coupled to another element, the element may be
directly connected to the other element or indirectly connected to
the other element via intervening elements. When an element is
referred to as being directly connected to another element, then
there are no intervening elements between the element and the other
element. Two devices are "in communication" if they are directly or
indirectly connected so that they can communicate electronic
signals between them.
[0184] For purposes of this document, the term "based on" may be
read as "based at least in part on."
[0185] For purposes of this document, without additional context,
use of numerical terms such as a "first" object, a "second" object,
and a "third" object may not imply an ordering of objects, but may
instead be used for identification purposes to identify different
objects.
[0186] The foregoing detailed description has been presented for
purposes of illustration and description. It is not intended to be
exhaustive or to limit the subject matter claimed herein to the
precise form(s) disclosed. Many modifications and variations are
possible in light of the above teachings. The described embodiments
were chosen in order to best explain the principles of the
disclosed technology and its practical application to thereby
enable others skilled in the art to best utilize the technology in
various embodiments and with various modifications as are suited to
the particular use contemplated. It is intended that the scope be
defined by the claims appended hereto.
[0187] Although the subject matter has been described in language
specific to structural features and/or methodological acts, it is
to be understood that the subject matter defined in the appended
claims is not necessarily limited to the specific features or acts
described above. Rather, the specific features and acts described
above are disclosed as example forms of implementing the
claims.
* * * * *